Some updates. API still in flux, but you can build

- Added support for Image
- Added a QuickLook feature, to enable thumbnail generation.
- Added support for NSButton.
- Fixed a bug where App activation under Big Sur would leave menus
  without the ability to be used.
- Added the ability for Buttons and ToolbarItems to execute callbacks.
- Added support for Labels and TextFields.
- Added support for MenuItems to have callbacks as well.
- Preliminary ListView support; you have to cache your ListViewRow items
  yourself for the time being, but it works.
- Animation support for ListView operations.
- Support for ScrollViews.
- Helpers for dispatching actions to the main thread (for UI work).
- Updated the Dispatcher trait to make thread handling simpler.
- Basic font support.

build.rs

@@ -1,14 +1,13 @@
-//! Specifies various frameworks to link against. Note that this is something where you probably
-//! only want to be compiling this project on macOS. ;P
+//! Emits linker flags depending on platforms and features.
 //!
-//! (it checks to see if it's macOS before emitting anything, but still)
+//! (iOS/macOS only right now... maybe tvOS one day?)
 
 fn main() {
     let target = std::env::var("TARGET").unwrap();
 
     println!("cargo:rustc-link-lib=framework=Foundation");
     
-    if std::env::var("TARGET").unwrap().contains("-ios") {
+    if target.contains("-ios") {
         println!("cargo:rustc-link-lib=framework=UIKit");
     } else {
         println!("cargo:rustc-link-lib=framework=AppKit");
@@ -16,7 +15,6 @@ fn main() {
 
     println!("cargo:rustc-link-lib=framework=CoreGraphics");
     println!("cargo:rustc-link-lib=framework=QuartzCore");
-
     println!("cargo:rustc-link-lib=framework=Security");
 
     #[cfg(feature = "webview")]
@@ -27,4 +25,7 @@ fn main() {
 
     #[cfg(feature = "user-notifications")]
     println!("cargo:rustc-link-lib=framework=UserNotifications");
+    
+    #[cfg(feature = "quicklook")]
+    println!("cargo:rustc-link-lib=framework=QuickLook");
 }

src/button.rs

@@ -1,19 +1,49 @@
 //! A wrapper for NSButton. Currently the epitome of jank - if you're poking around here, expect
 //! that this will change at some point.
 
+use std::fmt;
 use std::sync::Once;
 
-use objc_id::Id;
+use objc_id::ShareId;
 use objc::declare::ClassDecl;
-use objc::runtime::{Class, Object};
+use objc::runtime::{Class, Object, Sel};
 use objc::{class, msg_send, sel, sel_impl};
 
-use crate::foundation::{nil, NSString};
+use crate::foundation::{id, nil, BOOL, YES, NO, NSString};
+use crate::invoker::TargetActionHandler;
+use crate::layout::{Layout, LayoutAnchorX, LayoutAnchorY, LayoutAnchorDimension};
+use crate::utils::load;
 
 /// A wrapper for `NSButton`. Holds (retains) pointers for the Objective-C runtime 
 /// where our `NSButton` lives.
+#[derive(Debug)]
 pub struct Button {
-    pub objc: Id<Object>
+    pub objc: ShareId<Object>,
+    handler: Option<TargetActionHandler>,
+    
+    /// A pointer to the Objective-C runtime top layout constraint.
+    pub top: LayoutAnchorY,
+
+    /// A pointer to the Objective-C runtime leading layout constraint.
+    pub leading: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime trailing layout constraint.
+    pub trailing: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime bottom layout constraint.
+    pub bottom: LayoutAnchorY,
+
+    /// A pointer to the Objective-C runtime width layout constraint.
+    pub width: LayoutAnchorDimension,
+
+    /// A pointer to the Objective-C runtime height layout constraint.
+    pub height: LayoutAnchorDimension,
+
+    /// A pointer to the Objective-C runtime center X layout constraint.
+    pub center_x: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime center Y layout constraint.
+    pub center_y: LayoutAnchorY
 }
 
 impl Button {
@@ -21,12 +51,24 @@ impl Button {
     /// and retains the necessary Objective-C runtime pointer.
     pub fn new(text: &str) -> Self {
         let title = NSString::new(text);
-        let objc = unsafe {
-            Id::from_ptr(msg_send![register_class(), buttonWithTitle:title target:nil action:nil])
+
+        let view: id = unsafe {
+            let button: id = msg_send![register_class(), buttonWithTitle:title target:nil action:nil];
+            let _: () = msg_send![button, setTranslatesAutoresizingMaskIntoConstraints:NO];
+            button
         };
         
         Button {
-            objc: objc
+            handler: None,
+            top: LayoutAnchorY::new(unsafe { msg_send![view, topAnchor] }),
+            leading: LayoutAnchorX::new(unsafe { msg_send![view, leadingAnchor] }),
+            trailing: LayoutAnchorX::new(unsafe { msg_send![view, trailingAnchor] }),
+            bottom: LayoutAnchorY::new(unsafe { msg_send![view, bottomAnchor] }),
+            width: LayoutAnchorDimension::new(unsafe { msg_send![view, widthAnchor] }),
+            height: LayoutAnchorDimension::new(unsafe { msg_send![view, heightAnchor] }),
+            center_x: LayoutAnchorX::new(unsafe { msg_send![view, centerXAnchor] }),
+            center_y: LayoutAnchorY::new(unsafe { msg_send![view, centerYAnchor] }),
+            objc: unsafe { ShareId::from_ptr(view) },
         }
     }
 
@@ -36,10 +78,43 @@ impl Button {
             let _: () = msg_send![&*self.objc, setBezelStyle:bezel_style];
         }
     }
+
+    /// Attaches a callback for button press events. Don't get too creative now...
+    /// best just to message pass or something.
+    pub fn set_action<F: Fn() + Send + Sync + 'static>(&mut self, action: F) {
+        let handler = TargetActionHandler::new(&*self.objc, action);
+        self.handler = Some(handler);
+    }
 }
 
-/// Registers an `NSButton` subclass, and configures it to hold some ivars for various things we need
-/// to store.
+impl Layout for Button {
+    fn get_backing_node(&self) -> ShareId<Object> {
+        self.objc.clone()
+    }
+
+    fn add_subview<V: Layout>(&self, view: &V) {
+        /*let backing_node = view.get_backing_node();
+
+        unsafe {
+            let _: () = msg_send![&*self.objc, addSubview:backing_node];
+        }*/
+    }
+}
+
+
+impl Drop for Button {
+    // Just to be sure, let's... nil these out. They should be weak references,
+    // but I'd rather be paranoid and remove them later.
+    fn drop(&mut self) {
+        unsafe {
+            let _: () = msg_send![&*self.objc, setTarget:nil];
+            let _: () = msg_send![&*self.objc, setAction:nil];
+        }
+    }
+}
+
+/// Registers an `NSButton` subclass, and configures it to hold some ivars 
+/// for various things we need to store.
 fn register_class() -> *const Class {
     static mut VIEW_CLASS: *const Class = 0 as *const Class;
     static INIT: Once = Once::new();

src/dragdrop.rs

@@ -4,7 +4,7 @@
 
 use objc::runtime::Object;
 use objc::{msg_send, sel, sel_impl};
-use objc_id::Id;
+use objc_id::ShareId;
 
 use crate::foundation::NSUInteger;
 use crate::pasteboard::Pasteboard;
@@ -54,7 +54,7 @@ impl From<DragOperation> for NSUInteger {
 /// A wrapper for `NSDraggingInfo`. As this is a protocol/type you should never create yourself,
 /// this only provides getters - merely a Rust-y way to grab what you need.
 pub struct DragInfo {
-    pub info: Id<Object>
+    pub info: ShareId<Object>
 }
 
 impl DragInfo {

src/foundation/array.rs

@@ -49,7 +49,7 @@ impl NSArray {
     /// This handles that edge case.
     pub fn wrap(array: id) -> Self {
         NSArray(unsafe {
-            Id::from_retained_ptr(array)
+            Id::from_ptr(array)
         })
     }
 

src/image/handle.rs

@@ -0,0 +1,54 @@
+
+use objc_id::ShareId;
+use objc::runtime::Object;
+
+/// Views get passed these, and can 
+#[derive(Debug)]
+pub struct ViewHandle<T> {
+    /// A pointer to the Objective-C runtime view controller.
+    pub objc: ShareId<Object>,
+
+    _t: std::marker::PhantomData<T>
+
+    /// A pointer to the Objective-C runtime top layout constraint.
+    pub top: LayoutAnchorY,
+
+    /// A pointer to the Objective-C runtime leading layout constraint.
+    pub leading: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime trailing layout constraint.
+    pub trailing: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime bottom layout constraint.
+    pub bottom: LayoutAnchorY,
+
+    /// A pointer to the Objective-C runtime width layout constraint.
+    pub width: LayoutAnchorDimension,
+
+    /// A pointer to the Objective-C runtime height layout constraint.
+    pub height: LayoutAnchorDimension,
+
+    /// A pointer to the Objective-C runtime center X layout constraint.
+    pub center_x: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime center Y layout constraint.
+    pub center_y: LayoutAnchorY
+}
+
+impl<T> TextControl for ViewHandle<T>
+where
+    T: 
+
+impl<T> Layout for ViewHandle<T> {
+    fn get_backing_node(&self) -> ShareId<Object> {
+        self.objc.clone()
+    }
+
+    fn add_subview<V: Layout>(&self, view: &V) {
+        let backing_node = view.get_backing_node();
+
+        unsafe {
+            let _: () = msg_send![&*self.objc, addSubview:backing_node];
+        }
+    }
+}

src/image/image.rs

@@ -0,0 +1,16 @@
+use objc_id::ShareId;
+use objc::runtime::Object;
+
+use crate::foundation::{id};
+
+#[derive(Clone, Debug)]
+pub struct Image(pub ShareId<Object>);
+
+impl Image {
+    pub fn with(image: id) -> Self {
+        Image(unsafe {
+            ShareId::from_ptr(image)
+        })
+    }
+}
+

src/image/ios.rs

@@ -0,0 +1,45 @@
+use std::sync::Once;
+
+use objc::declare::ClassDecl;
+use objc::runtime::{Class, Object, Sel, BOOL};
+use objc::{class, sel, sel_impl};
+use objc_id::Id;
+
+use crate::foundation::{id, YES, NO, NSUInteger};
+use crate::dragdrop::DragInfo;
+use crate::view::{VIEW_DELEGATE_PTR, ViewDelegate};
+use crate::utils::load;
+
+/// Injects an `NSView` subclass. This is used for the default views that don't use delegates - we
+/// have separate classes here since we don't want to waste cycles on methods that will never be
+/// used if there's no delegates.
+pub(crate) fn register_view_class() -> *const Class {
+    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    static INIT: Once = Once::new();
+
+    INIT.call_once(|| unsafe {
+        let superclass = class!(UIView);
+        let mut decl = ClassDecl::new("RSTView", superclass).unwrap();
+        VIEW_CLASS = decl.register();
+    });
+
+    unsafe { VIEW_CLASS }
+}
+
+/// Injects an `NSView` subclass, with some callback and pointer ivars for what we
+/// need to do.
+pub(crate) fn register_view_class_with_delegate<T: ViewDelegate>() -> *const Class {
+    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    static INIT: Once = Once::new();
+
+    INIT.call_once(|| unsafe {
+        let superclass = class!(UIView);
+        let mut decl = ClassDecl::new("RSTViewWithDelegate", superclass).unwrap();
+        decl.add_ivar::<usize>(VIEW_DELEGATE_PTR);
+        VIEW_CLASS = decl.register();
+    });
+
+    unsafe {
+        VIEW_CLASS
+    }
+}

src/image/macos.rs

@@ -0,0 +1,39 @@
+//! This module does one specific thing: register a custom `NSView` class that's... brought to the
+//! modern era.
+//!
+//! I kid, I kid.
+//!
+//! It just enforces that coordinates are judged from the top-left, which is what most people look
+//! for in the modern era. It also implements a few helpers for things like setting a background
+//! color, and enforcing layer backing by default.
+
+use std::sync::Once;
+
+use objc::declare::ClassDecl;
+use objc::runtime::{Class, Object, Sel, BOOL};
+use objc::{class, sel, sel_impl};
+use objc_id::Id;
+
+use crate::foundation::{id, YES, NO, NSUInteger};
+use crate::dragdrop::DragInfo;
+use crate::view::{VIEW_DELEGATE_PTR, ViewDelegate};
+use crate::utils::load;
+
+/// Injects an `NSView` subclass. This is used for the default views that don't use delegates - we
+/// have separate classes here since we don't want to waste cycles on methods that will never be
+/// used if there's no delegates.
+pub(crate) fn register_image_view_class() -> *const Class {
+    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    static INIT: Once = Once::new();
+
+    INIT.call_once(|| unsafe {
+        let superclass = class!(NSImageView);
+        let mut decl = ClassDecl::new("RSTImageView", superclass).unwrap();
+
+        //decl.add_method(sel!(isFlipped), enforce_normalcy as extern fn(&Object, _) -> BOOL);
+    
+        VIEW_CLASS = decl.register();
+    });
+
+    unsafe { VIEW_CLASS }
+}

src/image/mod.rs

@@ -0,0 +1,143 @@
+use objc_id::ShareId;
+use objc::runtime::{Class, Object};
+use objc::{msg_send, sel, sel_impl};
+
+use crate::foundation::{id, nil, YES, NO, NSArray, NSString};
+use crate::color::Color;
+use crate::layout::{Layout, LayoutAnchorX, LayoutAnchorY, LayoutAnchorDimension};
+
+#[cfg(target_os = "macos")]
+mod macos;
+
+#[cfg(target_os = "macos")]
+use macos::register_image_view_class;
+
+#[cfg(target_os = "ios")]
+mod ios;
+
+#[cfg(target_os = "ios")]
+use ios::register_image_view_class;
+
+mod image;
+pub use image::Image;
+
+/// A helper method for instantiating view classes and applying default settings to them.
+fn allocate_view(registration_fn: fn() -> *const Class) -> id { 
+    unsafe {
+        let view: id = msg_send![registration_fn(), new];
+        let _: () = msg_send![view, setTranslatesAutoresizingMaskIntoConstraints:NO];
+
+        #[cfg(target_os = "macos")]
+        let _: () = msg_send![view, setWantsLayer:YES];
+
+        view 
+    }
+}
+
+/// A clone-able handler to a `ViewController` reference in the Objective C runtime. We use this
+/// instead of a stock `View` for easier recordkeeping, since it'll need to hold the `View` on that
+/// side anyway.
+#[derive(Debug)]
+pub struct ImageView {
+    /// A pointer to the Objective-C runtime view controller.
+    pub objc: ShareId<Object>,
+
+    /// A pointer to the Objective-C runtime top layout constraint.
+    pub top: LayoutAnchorY,
+
+    /// A pointer to the Objective-C runtime leading layout constraint.
+    pub leading: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime trailing layout constraint.
+    pub trailing: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime bottom layout constraint.
+    pub bottom: LayoutAnchorY,
+
+    /// A pointer to the Objective-C runtime width layout constraint.
+    pub width: LayoutAnchorDimension,
+
+    /// A pointer to the Objective-C runtime height layout constraint.
+    pub height: LayoutAnchorDimension,
+
+    /// A pointer to the Objective-C runtime center X layout constraint.
+    pub center_x: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime center Y layout constraint.
+    pub center_y: LayoutAnchorY
+}
+
+impl Default for ImageView {
+    fn default() -> Self {
+        ImageView::new()
+    }
+}
+
+impl ImageView {
+    /// Returns a default `View`, suitable for 
+    pub fn new() -> Self {
+        let view = allocate_view(register_image_view_class);
+
+        ImageView {
+            top: LayoutAnchorY::new(unsafe { msg_send![view, topAnchor] }),
+            leading: LayoutAnchorX::new(unsafe { msg_send![view, leadingAnchor] }),
+            trailing: LayoutAnchorX::new(unsafe { msg_send![view, trailingAnchor] }),
+            bottom: LayoutAnchorY::new(unsafe { msg_send![view, bottomAnchor] }),
+            width: LayoutAnchorDimension::new(unsafe { msg_send![view, widthAnchor] }),
+            height: LayoutAnchorDimension::new(unsafe { msg_send![view, heightAnchor] }),
+            center_x: LayoutAnchorX::new(unsafe { msg_send![view, centerXAnchor] }),
+            center_y: LayoutAnchorY::new(unsafe { msg_send![view, centerYAnchor] }),
+            objc: unsafe { ShareId::from_ptr(view) },
+        }
+    }
+
+    /// Call this to set the background color for the backing layer.
+    pub fn set_background_color(&self, color: Color) {
+        let bg = color.into_platform_specific_color();
+        
+        unsafe {
+            let cg: id = msg_send![bg, CGColor];
+            let layer: id = msg_send![&*self.objc, layer];
+            let _: () = msg_send![layer, setBackgroundColor:cg];
+        }
+    }
+
+    pub fn set_image(&self, image: &Image) {
+        unsafe {
+            let _: () = msg_send![&*self.objc, setImage:&*image.0];
+        }
+    }
+}
+
+impl Layout for ImageView {
+    fn get_backing_node(&self) -> ShareId<Object> {
+        self.objc.clone()
+    }
+
+    fn add_subview<V: Layout>(&self, view: &V) {
+        let backing_node = view.get_backing_node();
+
+        unsafe {
+            let _: () = msg_send![&*self.objc, addSubview:backing_node];
+        }
+    }
+}
+
+impl Drop for ImageView {
+    /// A bit of extra cleanup for delegate callback pointers. If the originating `View` is being
+    /// dropped, we do some logic to clean it all up (e.g, we go ahead and check to see if
+    /// this has a superview (i.e, it's in the heirarchy) on the AppKit side. If it does, we go
+    /// ahead and remove it - this is intended to match the semantics of how Rust handles things).
+    ///
+    /// There are, thankfully, no delegates we need to break here.
+    fn drop(&mut self) {
+        /*if self.delegate.is_some() {
+            unsafe {
+                let superview: id = msg_send![&*self.objc, superview];
+                if superview != nil {
+                    let _: () = msg_send![&*self.objc, removeFromSuperview];
+                }
+            }
+        }*/
+    }
+}

src/image/traits.rs

@@ -0,0 +1,39 @@
+//! Various traits used for Views.
+
+use crate::dragdrop::{DragInfo, DragOperation};
+use crate::view::View;
+
+pub trait ViewDelegate {
+    /// Called when the View is ready to work with. You're passed a `View` - this is safe to
+    /// store and use repeatedly, but it's not thread safe - any UI calls must be made from the
+    /// main thread!
+    fn did_load(&mut self, _view: View) {}
+
+    /// Called when this is about to be added to the view heirarchy.
+    fn will_appear(&self, _animated: bool) {}
+
+    /// Called after this has been added to the view heirarchy.
+    fn did_appear(&self, _animated: bool) {}
+
+    /// Called when this is about to be removed from the view heirarchy.
+    fn will_disappear(&self, _animated: bool) {}
+
+    /// Called when this has been removed from the view heirarchy.
+    fn did_disappear(&self, _animated: bool) {}
+
+    /// Invoked when the dragged image enters destination bounds or frame; returns dragging operation to perform.
+    fn dragging_entered(&self, _info: DragInfo) -> DragOperation { DragOperation::None }
+    
+    /// Invoked when the image is released, allowing the receiver to agree to or refuse drag operation.
+    fn prepare_for_drag_operation(&self, _info: DragInfo) -> bool { false }
+
+    /// Invoked after the released image has been removed from the screen, signaling the receiver to import the pasteboard data.
+    fn perform_drag_operation(&self, _info: DragInfo) -> bool { false }
+
+    /// Invoked when the dragging operation is complete, signaling the receiver to perform any necessary clean-up.
+    fn conclude_drag_operation(&self, _info: DragInfo) {}
+
+    /// Invoked when the dragged image exits the destination’s bounds rectangle (in the case of a view) or its frame 
+    /// rectangle (in the case of a window object).
+    fn dragging_exited(&self, _info: DragInfo) {}
+}

src/input/macos.rs

@@ -0,0 +1,58 @@
+//! This module does one specific thing: register a custom `NSView` class that's... brought to the
+//! modern era.
+//!
+//! I kid, I kid.
+//!
+//! It just enforces that coordinates are judged from the top-left, which is what most people look
+//! for in the modern era. It also implements a few helpers for things like setting a background
+//! color, and enforcing layer backing by default.
+
+use std::sync::Once;
+
+use objc::declare::ClassDecl;
+use objc::runtime::{Class, Object, Sel, BOOL};
+use objc::{class, sel, sel_impl};
+use objc_id::Id;
+
+use crate::foundation::{id, YES, NO, NSUInteger};
+use crate::dragdrop::DragInfo;
+use crate::input::{TEXTFIELD_DELEGATE_PTR, TextFieldDelegate};
+use crate::utils::load;
+
+/// Injects an `NSTextField` subclass. This is used for the default views that don't use delegates - we
+/// have separate classes here since we don't want to waste cycles on methods that will never be
+/// used if there's no delegates.
+pub(crate) fn register_view_class() -> *const Class {
+    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    static INIT: Once = Once::new();
+
+    INIT.call_once(|| unsafe {
+        let superclass = class!(NSTextField);
+        let mut decl = ClassDecl::new("RSTTextInputField", superclass).unwrap();
+        VIEW_CLASS = decl.register();
+    });
+
+    unsafe { VIEW_CLASS }
+}
+
+/// Injects an `NSTextField` subclass, with some callback and pointer ivars for what we
+/// need to do.
+pub(crate) fn register_view_class_with_delegate<T: TextFieldDelegate>() -> *const Class {
+    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    static INIT: Once = Once::new();
+
+    INIT.call_once(|| unsafe {
+        let superclass = class!(NSView);
+        let mut decl = ClassDecl::new("RSTTextInputFieldWithDelegate", superclass).unwrap();
+
+        // A pointer to the "view controller" on the Rust side. It's expected that this doesn't
+        // move.
+        decl.add_ivar::<usize>(TEXTFIELD_DELEGATE_PTR);        
+       
+        VIEW_CLASS = decl.register();
+    });
+
+    unsafe {
+        VIEW_CLASS
+    }
+}

src/input/mod.rs

@@ -0,0 +1,274 @@
+//! Wraps `NSTextField` and `UITextField` across platforms, explicitly as a TextField.
+//! In AppKit, `NSTextField` does double duty, and for clarity we just double
+//! the implementation.
+//!
+//! TextFields implement Autolayout, which enable you to specify how things should appear on the screen.
+//! 
+//! ```rust,no_run
+//! use cacao::color::rgb;
+//! use cacao::layout::{Layout, LayoutConstraint};
+//! use cacao::view::TextField;
+//! use cacao::window::{Window, WindowDelegate};
+//!
+//! #[derive(Default)]
+//! struct AppWindow {
+//!     content: TextField,
+//!     label: TextField,
+//!     window: Window
+//! }
+//! 
+//! impl WindowDelegate for AppWindow {
+//!     fn did_load(&mut self, window: Window) {
+//!         window.set_minimum_content_size(300., 300.);
+//!         self.window = window;
+//!
+//!         self.label.set_background_color(rgb(224, 82, 99));
+//!         self.label.set_text("LOL");
+//!         self.content.add_subview(&self.red);
+//!         
+//!         self.window.set_content_view(&self.content);
+//!
+//!         LayoutConstraint::activate(&[
+//!             self.red.top.constraint_equal_to(&self.content.top).offset(16.),
+//!             self.red.leading.constraint_equal_to(&self.content.leading).offset(16.),
+//!             self.red.trailing.constraint_equal_to(&self.content.trailing).offset(-16.),
+//!             self.red.bottom.constraint_equal_to(&self.content.bottom).offset(-16.),
+//!         ]);
+//!     }
+//! }
+//! ```
+//!
+//! For more information on Autolayout, view the module or check out the examples folder.
+
+use objc_id::ShareId;
+use objc::runtime::{Class, Object};
+use objc::{msg_send, sel, sel_impl};
+
+use crate::foundation::{id, nil, YES, NO, NSArray, NSInteger, NSString};
+use crate::color::Color;
+use crate::layout::{Layout, LayoutAnchorX, LayoutAnchorY, LayoutAnchorDimension};
+use crate::text::{Font, TextAlign};
+
+#[cfg(target_os = "macos")]
+mod macos;
+
+#[cfg(target_os = "macos")]
+use macos::{register_view_class, register_view_class_with_delegate};
+
+#[cfg(target_os = "ios")]
+mod ios;
+
+#[cfg(target_os = "ios")]
+use ios::{register_view_class, register_view_class_with_delegate};
+
+//mod controller;
+//pub use controller::TextFieldController;
+
+mod traits;
+pub use traits::TextFieldDelegate;
+
+pub(crate) static TEXTFIELD_DELEGATE_PTR: &str = "rstTextFieldDelegatePtr";
+
+/// A helper method for instantiating view classes and applying default settings to them.
+fn allocate_view(registration_fn: fn() -> *const Class) -> id { 
+    unsafe {
+        let view: id = msg_send![registration_fn(), new];
+
+        let _: () = msg_send![view, setTranslatesAutoresizingMaskIntoConstraints:NO];
+
+        #[cfg(target_os = "macos")]
+        let _: () = msg_send![view, setWantsLayer:YES];
+
+        view 
+    }
+}
+
+/// A clone-able handler to an `NSTextField/UITextField` reference in the 
+/// Objective-C runtime.
+#[derive(Debug)]
+pub struct TextField<T = ()> {
+    /// A pointer to the Objective-C runtime view controller.
+    pub objc: ShareId<Object>,
+
+    /// A pointer to the delegate for this view.
+    pub delegate: Option<Box<T>>,
+
+    /// A pointer to the Objective-C runtime top layout constraint.
+    pub top: LayoutAnchorY,
+
+    /// A pointer to the Objective-C runtime leading layout constraint.
+    pub leading: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime trailing layout constraint.
+    pub trailing: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime bottom layout constraint.
+    pub bottom: LayoutAnchorY,
+
+    /// A pointer to the Objective-C runtime width layout constraint.
+    pub width: LayoutAnchorDimension,
+
+    /// A pointer to the Objective-C runtime height layout constraint.
+    pub height: LayoutAnchorDimension,
+
+    /// A pointer to the Objective-C runtime center X layout constraint.
+    pub center_x: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime center Y layout constraint.
+    pub center_y: LayoutAnchorY
+}
+
+impl Default for TextField {
+    fn default() -> Self {
+        TextField::new()
+    }
+}
+
+impl TextField {
+    /// Returns a default `TextField`, suitable for 
+    pub fn new() -> Self {
+        let view = allocate_view(register_view_class);
+
+        TextField {
+            delegate: None,
+            top: LayoutAnchorY::new(unsafe { msg_send![view, topAnchor] }),
+            leading: LayoutAnchorX::new(unsafe { msg_send![view, leadingAnchor] }),
+            trailing: LayoutAnchorX::new(unsafe { msg_send![view, trailingAnchor] }),
+            bottom: LayoutAnchorY::new(unsafe { msg_send![view, bottomAnchor] }),
+            width: LayoutAnchorDimension::new(unsafe { msg_send![view, widthAnchor] }),
+            height: LayoutAnchorDimension::new(unsafe { msg_send![view, heightAnchor] }),
+            center_x: LayoutAnchorX::new(unsafe { msg_send![view, centerXAnchor] }),
+            center_y: LayoutAnchorY::new(unsafe { msg_send![view, centerYAnchor] }),
+            objc: unsafe { ShareId::from_ptr(view) },
+        }
+    }
+}
+
+impl<T> TextField<T> where T: TextFieldDelegate + 'static {
+    /// Initializes a new TextField with a given `TextFieldDelegate`. This enables you to respond to events
+    /// and customize the view as a module, similar to class-based systems.
+    pub fn with(delegate: T) -> TextField<T> {
+        let delegate = Box::new(delegate);
+        
+        let label = allocate_view(register_view_class_with_delegate::<T>);
+        unsafe {
+            //let view: id = msg_send![register_view_class_with_delegate::<T>(), new];
+            //let _: () = msg_send![view, setTranslatesAutoresizingMaskIntoConstraints:NO];
+            let ptr: *const T = &*delegate;
+            (&mut *label).set_ivar(TEXTFIELD_DELEGATE_PTR, ptr as usize);
+        };
+
+        let mut label = TextField {
+            delegate: None,
+            top: LayoutAnchorY::new(unsafe { msg_send![label, topAnchor] }),
+            leading: LayoutAnchorX::new(unsafe { msg_send![label, leadingAnchor] }),
+            trailing: LayoutAnchorX::new(unsafe { msg_send![label, trailingAnchor] }),
+            bottom: LayoutAnchorY::new(unsafe { msg_send![label, bottomAnchor] }),
+            width: LayoutAnchorDimension::new(unsafe { msg_send![label, widthAnchor] }),
+            height: LayoutAnchorDimension::new(unsafe { msg_send![label, heightAnchor] }),
+            center_x: LayoutAnchorX::new(unsafe { msg_send![label, centerXAnchor] }),
+            center_y: LayoutAnchorY::new(unsafe { msg_send![label, centerYAnchor] }),
+            objc: unsafe { ShareId::from_ptr(label) },
+        };
+
+        //(&mut delegate).did_load(label.clone_as_handle()); 
+        label.delegate = Some(delegate);
+        label
+    }
+}
+
+impl<T> TextField<T> {
+    /// An internal method that returns a clone of this object, sans references to the delegate or
+    /// callback pointer. We use this in calling `did_load()` - implementing delegates get a way to
+    /// reference, customize and use the view but without the trickery of holding pieces of the
+    /// delegate - the `TextField` is the only true holder of those.
+    pub(crate) fn clone_as_handle(&self) -> TextField {
+        TextField {
+            delegate: None,
+            top: self.top.clone(),
+            leading: self.leading.clone(),
+            trailing: self.trailing.clone(),
+            bottom: self.bottom.clone(),
+            width: self.width.clone(),
+            height: self.height.clone(),
+            center_x: self.center_x.clone(),
+            center_y: self.center_y.clone(),
+            objc: self.objc.clone()
+        }
+    }
+
+    /// Grabs the value from the textfield and returns it as an owned String.
+    pub fn get_value(&self) -> String {
+        let value = NSString::wrap(unsafe {
+            msg_send![&*self.objc, stringValue]
+        });
+
+        value.to_str().to_string()
+    }
+
+    /// Call this to set the background color for the backing layer.
+    pub fn set_background_color(&self, color: Color) {
+        let bg = color.into_platform_specific_color();
+        
+        unsafe {
+            let cg: id = msg_send![bg, CGColor];
+            let layer: id = msg_send![&*self.objc, layer];
+            let _: () = msg_send![layer, setBackgroundColor:cg];
+        }
+    }
+
+    /// Call this to set the text for the label.
+    pub fn set_text(&self, text: &str) {
+        let s = NSString::new(text);
+
+        unsafe {
+            let _: () = msg_send![&*self.objc, setStringValue:s.into_inner()];
+        }
+    }
+
+    pub fn set_text_alignment(&self, alignment: TextAlign) {
+        unsafe {
+            let alignment: NSInteger = alignment.into();
+            let _: () = msg_send![&*self.objc, setAlignment:alignment];
+        }
+    }
+
+    pub fn set_font(&self, font: &Font) {
+        unsafe {
+            let _: () = msg_send![&*self.objc, setFont:&*font.objc];
+        }
+    }
+}
+
+impl<T> Layout for TextField<T> {
+    fn get_backing_node(&self) -> ShareId<Object> {
+        self.objc.clone()
+    }
+
+    fn add_subview<V: Layout>(&self, view: &V) {
+        let backing_node = view.get_backing_node();
+
+        unsafe {
+            let _: () = msg_send![&*self.objc, addSubview:backing_node];
+        }
+    }
+}
+
+impl<T> Drop for TextField<T> {
+    /// A bit of extra cleanup for delegate callback pointers. If the originating `TextField` is being
+    /// dropped, we do some logic to clean it all up (e.g, we go ahead and check to see if
+    /// this has a superview (i.e, it's in the heirarchy) on the AppKit side. If it does, we go
+    /// ahead and remove it - this is intended to match the semantics of how Rust handles things).
+    ///
+    /// There are, thankfully, no delegates we need to break here.
+    fn drop(&mut self) {
+        if self.delegate.is_some() {
+            unsafe {
+                let superview: id = msg_send![&*self.objc, superview];
+                if superview != nil {
+                    let _: () = msg_send![&*self.objc, removeFromSuperview];
+                }
+            }
+        }
+    }
+}

src/input/traits.rs

@@ -0,0 +1,4 @@
+//! Various traits used for Labels.
+
+pub trait TextFieldDelegate {
+}

src/invoker.rs

@@ -0,0 +1,113 @@
+//! This module contains an NSObject subclass that can act as a generic target
+//! for action dispatch - e.g, for buttons, toolbars, etc. It loops back around
+//! to a Rust callback; you won't be able to necessarily use it like you would
+//! elsewhere, but you can message pass to achieve what you need.
+//!
+//! Note that this is explicitly intended to be 1:1 with a widget; it is not
+//! something you should ever attempt to clone or really bother interacting with.
+//! It is imperative that this drop whenever a corresponding control/widget
+//! is going away.
+
+use std::fmt;
+use std::sync::{Arc, Mutex, Once};
+
+use objc_id::ShareId;
+use objc::declare::ClassDecl;
+use objc::runtime::{Class, Object, Sel};
+use objc::{class, msg_send, sel, sel_impl};
+use block::{Block, ConcreteBlock, RcBlock};
+
+use crate::foundation::{id, nil, NSString};
+use crate::utils::load;
+
+pub static ACTION_CALLBACK_PTR: &str = "rstTargetActionPtr";
+
+/// An Action is just an indirection layer to get around Rust and optimizing
+/// zero-sum types; without this, pointers to callbacks will end up being 
+/// 0x1, and all point to whatever is there first (unsure if this is due to 
+/// Rust or Cocoa or what).
+///
+/// Point is, Button aren't created that much in the grand scheme of things,
+/// and the heap isn't our enemy in a GUI framework anyway. If someone knows 
+/// a better way to do this that doesn't require double-boxing, I'm all ears.
+pub struct Action(Box<Fn() + Send + Sync + 'static>);
+
+impl fmt::Debug for Action {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Action")
+            .finish()
+    }
+}
+
+/// A handler that contains the class for callback storage and invocation on
+/// the Objective-C side. 
+///
+/// This effectively wraps the target:action selector usage on NSControl and
+/// associated widgets.
+///
+/// Widgets that use this should keep it around; on drop,
+/// it _will_ remove your events somewhat transparently per Cocoa rules.
+#[derive(Debug)]
+pub struct TargetActionHandler {
+    action: Box<Action>,
+    invoker: ShareId<Object>
+}
+
+impl TargetActionHandler {
+    /// Returns a new TargetEventHandler.
+    pub fn new<F: Fn() + Send + Sync + 'static>(control: &Object, action: F) -> Self {
+        let block = Box::new(Action(Box::new(action)));
+        let ptr = Box::into_raw(block);
+
+        let invoker = unsafe {
+            ShareId::from_ptr({
+                let invoker: id = msg_send![register_invoker_class::<F>(), alloc];
+                let invoker: id = msg_send![invoker, init];
+                (&mut *invoker).set_ivar(ACTION_CALLBACK_PTR, ptr as usize);
+                let _: () = msg_send![control, setAction:sel!(perform:)];
+                let _: () = msg_send![control, setTarget:invoker];
+                invoker
+            })
+        };
+
+        TargetActionHandler {
+            invoker: invoker,
+            action: unsafe { Box::from_raw(ptr) }
+        }
+    }
+}
+
+/// This will fire for an NSButton callback.
+extern fn perform<F: Fn() + 'static>(this: &mut Object, _: Sel, _sender: id) {
+    let action = load::<Action>(this, ACTION_CALLBACK_PTR);
+    (action.0)();
+}
+
+/// Due to the way that Rust and Objective-C live... very different lifestyles,
+/// we need to find a way to make events work without _needing_ the whole 
+/// target/action setup you'd use in a standard Cocoa/AppKit/UIKit app.
+///
+/// Here, we inject a subclass that can store a pointer for a callback. We use 
+/// this as our target/action combo, which allows passing a 
+/// generic block over. It's still Rust, so you can't do crazy callbacks, but 
+/// you can at least fire an event off and do something.
+///
+/// The `NSButton` owns this object on instantiation, and will release it
+/// on drop. We handle the heap copy on the Rust side, so setting the block
+/// is just an ivar.
+pub(crate) fn register_invoker_class<F: Fn() + 'static>() -> *const Class {
+    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    static INIT: Once = Once::new();
+
+    INIT.call_once(|| unsafe {
+        let superclass = class!(NSObject);
+        let mut decl = ClassDecl::new("RSTTargetActionHandler", superclass).unwrap();
+
+        decl.add_ivar::<usize>(ACTION_CALLBACK_PTR);
+        decl.add_method(sel!(perform:), perform::<F> as extern fn (&mut Object, _, id));
+        
+        VIEW_CLASS = decl.register();
+    });
+
+    unsafe { VIEW_CLASS }
+}

src/lib.rs

@@ -72,6 +72,12 @@ pub use core_foundation;
 pub use core_graphics;
 pub use objc;
 pub use url;
+pub use lazy_static;
+
+/// Until we figure out a better way to handle reusable views (i.e, the 
+/// "correct" way for a list view to work), just let the delegates pass
+/// back the pointer and handle keeping the pools for themselves.
+pub type Node = objc_id::ShareId<objc::runtime::Object>;
 
 #[cfg(feature = "macos")]
 pub mod macos;
@@ -92,10 +98,19 @@ pub mod defaults;
 pub mod filesystem;
 pub mod foundation;
 pub mod geometry;
+pub mod image;
+pub mod input;
+pub(crate) mod invoker;
 pub mod layout;
+pub mod listview;
 pub mod networking;
 pub mod notification_center;
 pub mod pasteboard;
+pub mod scrollview;
+pub mod text;
+
+#[cfg(feature = "quicklook")]
+pub mod quicklook;
 
 #[cfg(feature = "user-notifications")]
 pub mod user_notifications;

src/listview/enums.rs

@@ -0,0 +1,42 @@
+use crate::foundation::NSUInteger;
+
+/// This enum represents the different stock animations possible
+/// for ListView row operations. You can pass it to `insert_rows`
+/// and `remove_rows` - reloads don't get animations.
+pub enum ListViewAnimation {
+    /// No animation.
+    None,
+
+    /// Fades rows in and out.
+    Fade,
+
+    /// Creates a gap - this one is mostly useful during
+    /// drag and drop operations.
+    Gap,
+
+    /// Animates in or out by sliding upwards.
+    SlideUp,
+    
+    /// Animates in or out by sliding down.
+    SlideDown,
+
+    /// Animates in or out by sliding left.
+    SlideLeft,
+
+    /// Animates in or out by sliding right.
+    SlideRight
+}
+
+impl Into<NSUInteger> for ListViewAnimation {
+    fn into(self) -> NSUInteger {
+        match self {
+            ListViewAnimation::None => 0x0,
+            ListViewAnimation::Fade => 0x1,
+            ListViewAnimation::Gap => 0x2,
+            ListViewAnimation::SlideUp => 0x10,
+            ListViewAnimation::SlideDown => 0x20,
+            ListViewAnimation::SlideLeft => 0x30,
+            ListViewAnimation::SlideRight => 0x40
+        }
+    }
+}

src/listview/macos.rs

@@ -0,0 +1,163 @@
+//! This module does one specific thing: register a custom `NSView` class that's... brought to the
+//! modern era.
+//!
+//! I kid, I kid.
+//!
+//! It just enforces that coordinates are judged from the top-left, which is what most people look
+//! for in the modern era. It also implements a few helpers for things like setting a background
+//! color, and enforcing layer backing by default.
+
+use std::sync::Once;
+
+use objc::declare::ClassDecl;
+use objc::runtime::{Class, Object, Sel, BOOL};
+use objc::{class, sel, sel_impl, msg_send};
+use objc_id::Id;
+
+use crate::foundation::{id, YES, NO, NSInteger, NSUInteger};
+use crate::dragdrop::DragInfo;
+use crate::listview::{LISTVIEW_DELEGATE_PTR, ListViewDelegate};
+use crate::utils::load;
+
+/// Determines the number of items by way of the backing data source (the Rust struct).
+extern fn number_of_items<T: ListViewDelegate>(
+    this: &Object,
+    _: Sel,
+    _: id
+) -> NSInteger {
+    let view = load::<T>(this, LISTVIEW_DELEGATE_PTR);
+    view.number_of_items() as NSInteger
+}
+
+extern fn view_for_column<T: ListViewDelegate>(
+    this: &Object,
+    _: Sel,
+    table_view: id,
+    _: id,
+    item: NSInteger
+) -> id {
+    let view = load::<T>(this, LISTVIEW_DELEGATE_PTR);
+    let item = view.item(item as usize);
+
+    // A hacky method of returning the underlying pointer
+    // without Rust annoying us.
+    //
+    // @TODO: probably find a better way to do this. It's theoretically fine,
+    // as we *know* the underlying view will be retained by the NSTableView, so
+    // passing over one more won't really screw up retain counts.
+    unsafe {
+        msg_send![&*item, self]
+    }
+}
+
+/// Enforces normalcy, or: a needlessly cruel method in terms of the name. You get the idea though.
+extern fn enforce_normalcy(_: &Object, _: Sel) -> BOOL {
+    return YES;
+}
+
+/// Called when a drag/drop operation has entered this view.
+extern fn dragging_entered<T: ListViewDelegate>(this: &mut Object, _: Sel, info: id) -> NSUInteger {
+    let view = load::<T>(this, LISTVIEW_DELEGATE_PTR);
+    view.dragging_entered(DragInfo {
+        info: unsafe { Id::from_ptr(info) }
+    }).into()
+}
+
+/// Called when a drag/drop operation has entered this view.
+extern fn prepare_for_drag_operation<T: ListViewDelegate>(this: &mut Object, _: Sel, info: id) -> BOOL {
+    let view = load::<T>(this, LISTVIEW_DELEGATE_PTR);
+    
+    match view.prepare_for_drag_operation(DragInfo {
+        info: unsafe { Id::from_ptr(info) }
+    }) {
+        true => YES,
+        false => NO
+    }
+}
+
+/// Called when a drag/drop operation has entered this view.
+extern fn perform_drag_operation<T: ListViewDelegate>(this: &mut Object, _: Sel, info: id) -> BOOL {
+    let view = load::<T>(this, LISTVIEW_DELEGATE_PTR);
+        
+    match view.perform_drag_operation(DragInfo {
+        info: unsafe { Id::from_ptr(info) }
+    }) {
+        true => YES,
+        false => NO
+    }
+}
+
+/// Called when a drag/drop operation has entered this view.
+extern fn conclude_drag_operation<T: ListViewDelegate>(this: &mut Object, _: Sel, info: id) {
+    let view = load::<T>(this, LISTVIEW_DELEGATE_PTR);
+    
+    view.conclude_drag_operation(DragInfo {
+        info: unsafe { Id::from_ptr(info) }
+    });           
+}
+
+/// Called when a drag/drop operation has entered this view.
+extern fn dragging_exited<T: ListViewDelegate>(this: &mut Object, _: Sel, info: id) {
+    let view = load::<T>(this, LISTVIEW_DELEGATE_PTR);
+        
+    view.dragging_exited(DragInfo {
+        info: unsafe { Id::from_ptr(info) }
+    });
+}
+
+/// Injects an `NSTableView` subclass, with some callback and pointer ivars for what we
+/// need to do. Note that we treat and constrain this as a one-column "list" view to match
+/// `UITableView` semantics; if `NSTableView`'s multi column behavior is needed, then it can
+/// be added in.
+pub(crate) fn register_listview_class() -> *const Class {
+    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    static INIT: Once = Once::new();
+
+    INIT.call_once(|| unsafe {
+        let superclass = class!(NSTableView);
+        let mut decl = ClassDecl::new("RSTListView", superclass).unwrap();
+       
+        VIEW_CLASS = decl.register();
+    });
+
+    unsafe {
+        VIEW_CLASS
+    }
+}
+
+/// Injects an `NSTableView` subclass, with some callback and pointer ivars for what we
+/// need to do. Note that we treat and constrain this as a one-column "list" view to match
+/// `UITableView` semantics; if `NSTableView`'s multi column behavior is needed, then it can
+/// be added in.
+pub(crate) fn register_listview_class_with_delegate<T: ListViewDelegate>() -> *const Class {
+    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    static INIT: Once = Once::new();
+
+    INIT.call_once(|| unsafe {
+        let superclass = class!(NSTableView);
+        let mut decl = ClassDecl::new("RSTListViewWithDelegate", superclass).unwrap();
+
+        // A pointer to the "view controller" on the Rust side. It's expected that this doesn't
+        // move.
+        decl.add_ivar::<usize>(LISTVIEW_DELEGATE_PTR);
+        
+        decl.add_method(sel!(isFlipped), enforce_normalcy as extern fn(&Object, _) -> BOOL);
+
+        // Tableview-specific
+        decl.add_method(sel!(numberOfRowsInTableView:), number_of_items::<T> as extern fn(&Object, _, id) -> NSInteger);
+        decl.add_method(sel!(tableView:viewForTableColumn:row:), view_for_column::<T> as extern fn(&Object, _, id, id, NSInteger) -> id);
+
+        // Drag and drop operations (e.g, accepting files)
+        decl.add_method(sel!(draggingEntered:), dragging_entered::<T> as extern fn (&mut Object, _, _) -> NSUInteger);
+        decl.add_method(sel!(prepareForDragOperation:), prepare_for_drag_operation::<T> as extern fn (&mut Object, _, _) -> BOOL);
+        decl.add_method(sel!(performDragOperation:), perform_drag_operation::<T> as extern fn (&mut Object, _, _) -> BOOL);
+        decl.add_method(sel!(concludeDragOperation:), conclude_drag_operation::<T> as extern fn (&mut Object, _, _));
+        decl.add_method(sel!(draggingExited:), dragging_exited::<T> as extern fn (&mut Object, _, _));
+        
+        VIEW_CLASS = decl.register();
+    });
+
+    unsafe {
+        VIEW_CLASS
+    }
+}

src/listview/mod.rs

@@ -0,0 +1,454 @@
+//! Wraps `NSView` and `UIView` across platforms.
+//!
+//! This implementation errs towards the `UIView` side of things, and mostly acts as a wrapper to
+//! bring `NSView` to the modern era. It does this by flipping the coordinate system to be what
+//! people expect in 2020, and layer-backing all views by default.
+//!
+//! Views implement Autolayout, which enable you to specify how things should appear on the screen.
+//! 
+//! ```rust,no_run
+//! use cacao::color::rgb;
+//! use cacao::layout::{Layout, LayoutConstraint};
+//! use cacao::view::View;
+//! use cacao::window::{Window, WindowDelegate};
+//!
+//! #[derive(Default)]
+//! struct AppWindow {
+//!     content: View,
+//!     red: View,
+//!     window: Window
+//! }
+//! 
+//! impl WindowDelegate for AppWindow {
+//!     fn did_load(&mut self, window: Window) {
+//!         window.set_minimum_content_size(300., 300.);
+//!         self.window = window;
+//!
+//!         self.red.set_background_color(rgb(224, 82, 99));
+//!         self.content.add_subview(&self.red);
+//!         
+//!         self.window.set_content_view(&self.content);
+//!
+//!         LayoutConstraint::activate(&[
+//!             self.red.top.constraint_equal_to(&self.content.top).offset(16.),
+//!             self.red.leading.constraint_equal_to(&self.content.leading).offset(16.),
+//!             self.red.trailing.constraint_equal_to(&self.content.trailing).offset(-16.),
+//!             self.red.bottom.constraint_equal_to(&self.content.bottom).offset(-16.),
+//!         ]);
+//!     }
+//! }
+//! ```
+//!
+//! For more information on Autolayout, view the module or check out the examples folder.
+
+use core_graphics::base::CGFloat;
+use objc_id::ShareId;
+use objc::runtime::{Class, Object};
+use objc::{class, msg_send, sel, sel_impl};
+
+use crate::foundation::{id, nil, YES, NO, NSArray, NSString, NSUInteger};
+use crate::color::Color;
+use crate::layout::{Layout, LayoutAnchorX, LayoutAnchorY, LayoutAnchorDimension};
+use crate::pasteboard::PasteboardType;
+use crate::scrollview::ScrollView;
+use crate::utils::CGSize;
+
+#[cfg(target_os = "macos")]
+mod macos;
+
+#[cfg(target_os = "macos")]
+use macos::{register_listview_class, register_listview_class_with_delegate};
+
+#[cfg(target_os = "ios")]
+mod ios;
+
+#[cfg(target_os = "ios")]
+use ios::{register_view_class, register_view_class_with_delegate};
+
+mod enums;
+pub use enums::ListViewAnimation;
+
+mod traits;
+pub use traits::ListViewDelegate;
+
+mod row;
+pub use row::ListViewRow;
+
+pub(crate) static LISTVIEW_DELEGATE_PTR: &str = "rstListViewDelegatePtr";
+
+/// A helper method for instantiating view classes and applying default settings to them.
+fn allocate_view(registration_fn: fn() -> *const Class) -> id { 
+    unsafe {
+        let tableview: id = msg_send![registration_fn(), new];
+        let _: () = msg_send![tableview, setTranslatesAutoresizingMaskIntoConstraints:NO];
+
+        // Let's... make NSTableView into UITableView-ish.
+        #[cfg(target_os = "macos")]
+        {
+            let _: () = msg_send![tableview, setWantsLayer:YES];
+            let _: () = msg_send![tableview, setUsesAutomaticRowHeights:YES];
+            let _: () = msg_send![tableview, setFloatsGroupRows:YES];
+            let _: () = msg_send![tableview, setIntercellSpacing:CGSize::new(0., 0.)];
+            let _: () = msg_send![tableview, setColumnAutoresizingStyle:1];
+            //msg_send![tableview, setSelectionHighlightStyle:-1];
+            let _: () = msg_send![tableview, setAllowsEmptySelection:YES];
+            let _: () = msg_send![tableview, setAllowsMultipleSelection:NO];
+            let _: () = msg_send![tableview, setHeaderView:nil];
+
+            // NSTableView requires at least one column to be manually added if doing so by code.
+            // A relic of a bygone era, indeed.
+            let identifier = NSString::new("CacaoListViewColumn");
+            let default_column_alloc: id = msg_send![class!(NSTableColumn), new];
+            let default_column: id = msg_send![default_column_alloc, initWithIdentifier:identifier.into_inner()];
+            let _: () = msg_send![default_column, setResizingMask:(1<<0)];
+            let _: () = msg_send![tableview, addTableColumn:default_column];
+        }
+
+        tableview
+    }
+}
+
+#[derive(Debug)]
+pub struct ListView<T = ()> {
+    /// A pointer to the Objective-C runtime view controller.
+    pub objc: ShareId<Object>,
+
+    /// On macOS, we need to manage the NSScrollView ourselves. It's a bit
+    /// more old school like that...
+    #[cfg(target_os = "macos")]
+    pub scrollview: ScrollView,
+
+    /// A pointer to the delegate for this view.
+    pub delegate: Option<Box<T>>,
+
+    /// A pointer to the Objective-C runtime top layout constraint.
+    pub top: LayoutAnchorY,
+
+    /// A pointer to the Objective-C runtime leading layout constraint.
+    pub leading: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime trailing layout constraint.
+    pub trailing: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime bottom layout constraint.
+    pub bottom: LayoutAnchorY,
+
+    /// A pointer to the Objective-C runtime width layout constraint.
+    pub width: LayoutAnchorDimension,
+
+    /// A pointer to the Objective-C runtime height layout constraint.
+    pub height: LayoutAnchorDimension,
+
+    /// A pointer to the Objective-C runtime center X layout constraint.
+    pub center_x: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime center Y layout constraint.
+    pub center_y: LayoutAnchorY
+}
+
+impl Default for ListView {
+    fn default() -> Self {
+        ListView::new()
+    }
+}
+
+impl ListView {
+    /// Returns a default `View`, suitable for 
+    pub fn new() -> Self {
+        let view = allocate_view(register_listview_class);
+        
+        #[cfg(target_os = "macos")]
+        let scrollview = {
+            let sview = ScrollView::new();
+            
+            unsafe {
+                let _: () = msg_send![&*sview.objc, setDocumentView:view];
+            }
+
+            sview
+        };
+
+        // For macOS, we need to use the NSScrollView anchor points, not the NSTableView.
+        #[cfg(target_os = "macos")]
+        let anchor_view = &*scrollview.objc;
+        
+        #[cfg(target_os = "ios")]
+        let anchor_view = view;
+
+        ListView {
+            delegate: None,
+            top: LayoutAnchorY::new(unsafe { msg_send![anchor_view, topAnchor] }),
+            leading: LayoutAnchorX::new(unsafe { msg_send![anchor_view, leadingAnchor] }),
+            trailing: LayoutAnchorX::new(unsafe { msg_send![anchor_view, trailingAnchor] }),
+            bottom: LayoutAnchorY::new(unsafe { msg_send![anchor_view, bottomAnchor] }),
+            width: LayoutAnchorDimension::new(unsafe { msg_send![anchor_view, widthAnchor] }),
+            height: LayoutAnchorDimension::new(unsafe { msg_send![anchor_view, heightAnchor] }),
+            center_x: LayoutAnchorX::new(unsafe { msg_send![anchor_view, centerXAnchor] }),
+            center_y: LayoutAnchorY::new(unsafe { msg_send![anchor_view, centerYAnchor] }),
+            objc: unsafe { ShareId::from_ptr(view) },
+
+            #[cfg(target_os = "macos")]
+            scrollview: scrollview
+        }
+    }
+}
+
+
+impl<T> ListView<T> where T: ListViewDelegate + 'static {
+    /// Initializes a new View with a given `ViewDelegate`. This enables you to respond to events
+    /// and customize the view as a module, similar to class-based systems.
+    pub fn with(delegate: T) -> ListView<T> {
+        let mut delegate = Box::new(delegate);
+        
+        let view = allocate_view(register_listview_class_with_delegate::<T>);
+        unsafe {
+            //let view: id = msg_send![register_view_class_with_delegate::<T>(), new];
+            //let _: () = msg_send![view, setTranslatesAutoresizingMaskIntoConstraints:NO];
+            let ptr: *const T = &*delegate;
+            (&mut *view).set_ivar(LISTVIEW_DELEGATE_PTR, ptr as usize);
+            let _: () = msg_send![view, setDelegate:view];
+            let _: () = msg_send![view, setDataSource:view];
+        };
+
+        #[cfg(target_os = "macos")]
+        let scrollview = {
+            let sview = ScrollView::new();
+            
+            unsafe {
+                let _: () = msg_send![&*sview.objc, setDocumentView:view];
+            }
+
+            sview
+        };
+
+        // For macOS, we need to use the NSScrollView anchor points, not the NSTableView.
+        #[cfg(target_os = "macos")]
+        let anchor_view = &*scrollview.objc;
+        
+        #[cfg(target_os = "ios")]
+        let anchor_view = view;
+
+        let mut view = ListView {
+            delegate: None,
+            top: LayoutAnchorY::new(unsafe { msg_send![anchor_view, topAnchor] }),
+            leading: LayoutAnchorX::new(unsafe { msg_send![anchor_view, leadingAnchor] }),
+            trailing: LayoutAnchorX::new(unsafe { msg_send![anchor_view, trailingAnchor] }),
+            bottom: LayoutAnchorY::new(unsafe { msg_send![anchor_view, bottomAnchor] }),
+            width: LayoutAnchorDimension::new(unsafe { msg_send![anchor_view, widthAnchor] }),
+            height: LayoutAnchorDimension::new(unsafe { msg_send![anchor_view, heightAnchor] }),
+            center_x: LayoutAnchorX::new(unsafe { msg_send![anchor_view, centerXAnchor] }),
+            center_y: LayoutAnchorY::new(unsafe { msg_send![anchor_view, centerYAnchor] }),
+            objc: unsafe { ShareId::from_ptr(view) },
+            
+            #[cfg(target_os = "macos")]
+            scrollview: scrollview
+        };
+
+        (&mut delegate).did_load(view.clone_as_handle()); 
+        view.delegate = Some(delegate);
+        view
+    }
+}
+
+impl<T> ListView<T> {
+    /// An internal method that returns a clone of this object, sans references to the delegate or
+    /// callback pointer. We use this in calling `did_load()` - implementing delegates get a way to
+    /// reference, customize and use the view but without the trickery of holding pieces of the
+    /// delegate - the `View` is the only true holder of those.
+    pub(crate) fn clone_as_handle(&self) -> ListView {
+        ListView {
+            delegate: None,
+            top: self.top.clone(),
+            leading: self.leading.clone(),
+            trailing: self.trailing.clone(),
+            bottom: self.bottom.clone(),
+            width: self.width.clone(),
+            height: self.height.clone(),
+            center_x: self.center_x.clone(),
+            center_y: self.center_y.clone(),
+            objc: self.objc.clone(),
+
+            #[cfg(target_os = "macos")]
+            scrollview: self.scrollview.clone_as_handle()
+        }
+    }
+
+    /// Call this to set the background color for the backing layer.
+    pub fn set_background_color(&self, color: Color) {
+        let bg = color.into_platform_specific_color();
+        
+        unsafe {
+            let cg: id = msg_send![bg, CGColor];
+            let layer: id = msg_send![&*self.objc, layer];
+            let _: () = msg_send![layer, setBackgroundColor:cg];
+        }
+    }
+
+    pub fn perform_batch_updates<F: Fn(ListView)>(&self, update: F) {
+        #[cfg(target_os = "macos")]
+        unsafe { 
+            let _: () = msg_send![&*self.objc, beginUpdates];
+           
+            let handle = self.clone_as_handle();
+            update(handle);
+
+            let _: () = msg_send![&*self.objc, endUpdates];
+        }
+    }
+
+    pub fn insert_rows<I: IntoIterator<Item = usize>>(&self, indexes: I, animations: ListViewAnimation) {
+        #[cfg(target_os = "macos")]
+        unsafe {
+            let index_set: id = msg_send![class!(NSMutableIndexSet), new];
+            
+            for index in indexes {
+                let x: NSUInteger = index as NSUInteger;
+                let _: () = msg_send![index_set, addIndex:x];
+            }
+
+            let animation_options: NSUInteger = animations.into();
+
+            // We need to temporarily retain this; it can drop after the underlying NSTableView
+            // has also retained it.
+            let x = ShareId::from_ptr(index_set);
+            let _: () = msg_send![&*self.objc, insertRowsAtIndexes:&*x withAnimation:20];
+        }
+    }
+
+    pub fn reload_rows(&self, indexes: &[usize]) {
+        #[cfg(target_os = "macos")]
+        unsafe {
+            let index_set: id = msg_send![class!(NSMutableIndexSet), new];
+            
+            for index in indexes {
+                let x: NSUInteger = *index as NSUInteger;
+                let _: () = msg_send![index_set, addIndex:x];
+            }
+
+            let x = ShareId::from_ptr(index_set);
+
+            let ye: id = msg_send![class!(NSIndexSet), indexSetWithIndex:0];
+            let y = ShareId::from_ptr(ye);
+            let _: () = msg_send![&*self.objc, reloadDataForRowIndexes:&*x columnIndexes:&*y];
+        }
+    }
+
+    pub fn remove_rows<I: IntoIterator<Item = usize>>(&self, indexes: I, animations: ListViewAnimation) {
+        #[cfg(target_os = "macos")]
+        unsafe {
+            let index_set: id = msg_send![class!(NSMutableIndexSet), new];
+            
+            for index in indexes {
+                let x: NSUInteger = index as NSUInteger;
+                let _: () = msg_send![index_set, addIndex:x];
+            }
+
+            let animation_options: NSUInteger = animations.into();
+
+            // We need to temporarily retain this; it can drop after the underlying NSTableView
+            // has also retained it.
+            let x = ShareId::from_ptr(index_set);
+            let _: () = msg_send![&*self.objc, removeRowsAtIndexes:&*x withAnimation:20];
+        }
+    }
+
+    /// Sets an enforced row-height; if you need dynamic rows, you'll want to
+    /// look at ListViewDelegate methods, or use AutoLayout.
+    pub fn set_row_height(&self, height: CGFloat) {
+        unsafe {
+            let _: () = msg_send![&*self.objc, setRowHeight:height];
+        }
+    }
+
+    /// This defaults to true. If you're using manual heights, you may want to set this to `false`,
+    /// as it will tell AppKit internally to just use the number instead of trying to judge
+    /// heights.
+    ///
+    /// It can make some scrolling situations much smoother.
+    pub fn set_uses_automatic_row_heights(&self, uses: bool) {
+        #[cfg(target_os = "macos")]
+        unsafe {
+            let _: () = msg_send![&*self.objc, setUsesAutomaticRowHeights:match uses {
+                true => YES,
+                false => NO
+            }];
+        }
+    }
+
+    /// On macOS, this will instruct the underlying NSTableView to alternate
+    /// background colors automatically. If you set this, you possibly want
+    /// to hard-set a row height as well.
+    pub fn set_uses_alternating_backgrounds(&self, uses: bool) {
+        #[cfg(target_os = "macos")]
+        unsafe {
+            let _: () = msg_send![&*self.objc, setUsesAlternatingRowBackgroundColors:match uses {
+                true => YES,
+                false => NO
+            }];
+        }
+    }
+
+    /// Register this view for drag and drop operations.
+    pub fn register_for_dragged_types(&self, types: &[PasteboardType]) {
+        unsafe {
+            let types: NSArray = types.into_iter().map(|t| {
+                // This clone probably doesn't need to be here, but it should also be cheap as
+                // this is just an enum... and this is not an oft called method.
+                let x: NSString = t.clone().into();
+                x.into_inner()
+            }).collect::<Vec<id>>().into();
+
+            let _: () = msg_send![&*self.objc, registerForDraggedTypes:types.into_inner()];
+        }
+    }
+
+    pub fn reload(&self) {
+        unsafe {
+            let _: () = msg_send![&*self.objc, reloadData];
+        }
+    }
+}
+
+impl<T> Layout for ListView<T> {
+    /// On macOS, this returns the NSScrollView, not the NSTableView.
+    fn get_backing_node(&self) -> ShareId<Object> {
+        #[cfg(target_os = "macos")]
+        let val = self.scrollview.objc.clone();
+
+        #[cfg(target_os = "ios")]
+        let val = self.objc.clone();
+
+        val
+    }
+
+    fn add_subview<V: Layout>(&self, view: &V) {
+        let backing_node = view.get_backing_node();
+
+        unsafe {
+            #[cfg(target_os = "macos")]
+            let _: () = msg_send![&*self.scrollview.objc, addSubview:backing_node];
+            
+            #[cfg(target_os = "ios")]
+            let _: () = msg_send![&*self.objc, addSubview:backing_node];
+        }
+    }
+}
+
+impl<T> Drop for ListView<T> {
+    /// A bit of extra cleanup for delegate callback pointers. If the originating `View` is being
+    /// dropped, we do some logic to clean it all up (e.g, we go ahead and check to see if
+    /// this has a superview (i.e, it's in the heirarchy) on the AppKit side. If it does, we go
+    /// ahead and remove it - this is intended to match the semantics of how Rust handles things).
+    ///
+    /// There are, thankfully, no delegates we need to break here.
+    fn drop(&mut self) {
+        if self.delegate.is_some() {
+            unsafe {
+                let superview: id = msg_send![&*self.objc, superview];
+                if superview != nil {
+                    let _: () = msg_send![&*self.objc, removeFromSuperview];
+                }
+            }
+        }
+    }
+}

src/listview/row/ios.rs

@@ -0,0 +1,45 @@
+use std::sync::Once;
+
+use objc::declare::ClassDecl;
+use objc::runtime::{Class, Object, Sel, BOOL};
+use objc::{class, sel, sel_impl};
+use objc_id::Id;
+
+use crate::foundation::{id, YES, NO, NSUInteger};
+use crate::dragdrop::DragInfo;
+use crate::view::{VIEW_DELEGATE_PTR, ViewDelegate};
+use crate::utils::load;
+
+/// Injects an `NSView` subclass. This is used for the default views that don't use delegates - we
+/// have separate classes here since we don't want to waste cycles on methods that will never be
+/// used if there's no delegates.
+pub(crate) fn register_view_class() -> *const Class {
+    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    static INIT: Once = Once::new();
+
+    INIT.call_once(|| unsafe {
+        let superclass = class!(UIView);
+        let mut decl = ClassDecl::new("RSTView", superclass).unwrap();
+        VIEW_CLASS = decl.register();
+    });
+
+    unsafe { VIEW_CLASS }
+}
+
+/// Injects an `NSView` subclass, with some callback and pointer ivars for what we
+/// need to do.
+pub(crate) fn register_view_class_with_delegate<T: ViewDelegate>() -> *const Class {
+    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    static INIT: Once = Once::new();
+
+    INIT.call_once(|| unsafe {
+        let superclass = class!(UIView);
+        let mut decl = ClassDecl::new("RSTViewWithDelegate", superclass).unwrap();
+        decl.add_ivar::<usize>(VIEW_DELEGATE_PTR);
+        VIEW_CLASS = decl.register();
+    });
+
+    unsafe {
+        VIEW_CLASS
+    }
+}

src/listview/row/macos.rs

@@ -0,0 +1,125 @@
+//! This module does one specific thing: register a custom `NSView` class that's... brought to the
+//! modern era.
+//!
+//! I kid, I kid.
+//!
+//! It just enforces that coordinates are judged from the top-left, which is what most people look
+//! for in the modern era. It also implements a few helpers for things like setting a background
+//! color, and enforcing layer backing by default.
+
+use std::sync::Once;
+
+use objc::declare::ClassDecl;
+use objc::runtime::{Class, Object, Sel, BOOL};
+use objc::{class, sel, sel_impl};
+use objc_id::Id;
+
+use crate::foundation::{id, YES, NO, NSUInteger};
+use crate::dragdrop::DragInfo;
+use crate::listview::row::{LISTVIEW_ROW_DELEGATE_PTR, ViewDelegate};
+use crate::utils::load;
+
+/// Enforces normalcy, or: a needlessly cruel method in terms of the name. You get the idea though.
+extern fn enforce_normalcy(_: &Object, _: Sel) -> BOOL {
+    return YES;
+}
+
+/// Called when a drag/drop operation has entered this view.
+extern fn dragging_entered<T: ViewDelegate>(this: &mut Object, _: Sel, info: id) -> NSUInteger {
+    let view = load::<T>(this, LISTVIEW_ROW_DELEGATE_PTR);
+    view.dragging_entered(DragInfo {
+        info: unsafe { Id::from_ptr(info) }
+    }).into()
+}
+
+/// Called when a drag/drop operation has entered this view.
+extern fn prepare_for_drag_operation<T: ViewDelegate>(this: &mut Object, _: Sel, info: id) -> BOOL {
+    let view = load::<T>(this, LISTVIEW_ROW_DELEGATE_PTR);
+    
+    match view.prepare_for_drag_operation(DragInfo {
+        info: unsafe { Id::from_ptr(info) }
+    }) {
+        true => YES,
+        false => NO
+    }
+}
+
+/// Called when a drag/drop operation has entered this view.
+extern fn perform_drag_operation<T: ViewDelegate>(this: &mut Object, _: Sel, info: id) -> BOOL {
+    let view = load::<T>(this, LISTVIEW_ROW_DELEGATE_PTR);
+        
+    match view.perform_drag_operation(DragInfo {
+        info: unsafe { Id::from_ptr(info) }
+    }) {
+        true => YES,
+        false => NO
+    }
+}
+
+/// Called when a drag/drop operation has entered this view.
+extern fn conclude_drag_operation<T: ViewDelegate>(this: &mut Object, _: Sel, info: id) {
+    let view = load::<T>(this, LISTVIEW_ROW_DELEGATE_PTR);
+    
+    view.conclude_drag_operation(DragInfo {
+        info: unsafe { Id::from_ptr(info) }
+    });           
+}
+
+/// Called when a drag/drop operation has entered this view.
+extern fn dragging_exited<T: ViewDelegate>(this: &mut Object, _: Sel, info: id) {
+    let view = load::<T>(this, LISTVIEW_ROW_DELEGATE_PTR);
+        
+    view.dragging_exited(DragInfo {
+        info: unsafe { Id::from_ptr(info) }
+    });
+}
+
+/// Injects an `NSView` subclass. This is used for the default views that don't use delegates - we
+/// have separate classes here since we don't want to waste cycles on methods that will never be
+/// used if there's no delegates.
+pub(crate) fn register_listview_row_class() -> *const Class {
+    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    static INIT: Once = Once::new();
+
+    INIT.call_once(|| unsafe {
+        let superclass = class!(NSView);
+        let mut decl = ClassDecl::new("RSTTableViewRow", superclass).unwrap();
+
+        decl.add_method(sel!(isFlipped), enforce_normalcy as extern fn(&Object, _) -> BOOL);
+    
+        VIEW_CLASS = decl.register();
+    });
+
+    unsafe { VIEW_CLASS }
+}
+
+/// Injects an `NSView` subclass, with some callback and pointer ivars for what we
+/// need to do.
+pub(crate) fn register_listview_row_class_with_delegate<T: ViewDelegate>() -> *const Class {
+    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    static INIT: Once = Once::new();
+
+    INIT.call_once(|| unsafe {
+        let superclass = class!(NSView);
+        let mut decl = ClassDecl::new("RSTableViewRowWithDelegate", superclass).unwrap();
+
+        // A pointer to the "view controller" on the Rust side. It's expected that this doesn't
+        // move.
+        decl.add_ivar::<usize>(LISTVIEW_ROW_DELEGATE_PTR);
+        
+        decl.add_method(sel!(isFlipped), enforce_normalcy as extern fn(&Object, _) -> BOOL);
+
+        // Drag and drop operations (e.g, accepting files)
+        decl.add_method(sel!(draggingEntered:), dragging_entered::<T> as extern fn (&mut Object, _, _) -> NSUInteger);
+        decl.add_method(sel!(prepareForDragOperation:), prepare_for_drag_operation::<T> as extern fn (&mut Object, _, _) -> BOOL);
+        decl.add_method(sel!(performDragOperation:), perform_drag_operation::<T> as extern fn (&mut Object, _, _) -> BOOL);
+        decl.add_method(sel!(concludeDragOperation:), conclude_drag_operation::<T> as extern fn (&mut Object, _, _));
+        decl.add_method(sel!(draggingExited:), dragging_exited::<T> as extern fn (&mut Object, _, _));
+        
+        VIEW_CLASS = decl.register();
+    });
+
+    unsafe {
+        VIEW_CLASS
+    }
+}

src/listview/row/mod.rs

@@ -0,0 +1,245 @@
+//! Wraps `NSView` and `UIView` across platforms.
+//!
+//! This implementation errs towards the `UIView` side of things, and mostly acts as a wrapper to
+//! bring `NSView` to the modern era. It does this by flipping the coordinate system to be what
+//! people expect in 2020, and layer-backing all views by default.
+//!
+//! Views implement Autolayout, which enable you to specify how things should appear on the screen.
+//! 
+//! ```rust,no_run
+//! use cacao::color::rgb;
+//! use cacao::layout::{Layout, LayoutConstraint};
+//! use cacao::view::View;
+//! use cacao::window::{Window, WindowDelegate};
+//!
+//! #[derive(Default)]
+//! struct AppWindow {
+//!     content: View,
+//!     red: View,
+//!     window: Window
+//! }
+//! 
+//! impl WindowDelegate for AppWindow {
+//!     fn did_load(&mut self, window: Window) {
+//!         window.set_minimum_content_size(300., 300.);
+//!         self.window = window;
+//!
+//!         self.red.set_background_color(rgb(224, 82, 99));
+//!         self.content.add_subview(&self.red);
+//!         
+//!         self.window.set_content_view(&self.content);
+//!
+//!         LayoutConstraint::activate(&[
+//!             self.red.top.constraint_equal_to(&self.content.top).offset(16.),
+//!             self.red.leading.constraint_equal_to(&self.content.leading).offset(16.),
+//!             self.red.trailing.constraint_equal_to(&self.content.trailing).offset(-16.),
+//!             self.red.bottom.constraint_equal_to(&self.content.bottom).offset(-16.),
+//!         ]);
+//!     }
+//! }
+//! ```
+//!
+//! For more information on Autolayout, view the module or check out the examples folder.
+
+use objc_id::ShareId;
+use objc::runtime::{Class, Object};
+use objc::{msg_send, sel, sel_impl};
+
+use crate::foundation::{id, nil, YES, NO, NSArray, NSString};
+use crate::color::Color;
+use crate::layout::{Layout, LayoutAnchorX, LayoutAnchorY, LayoutAnchorDimension};
+use crate::pasteboard::PasteboardType;
+use crate::view::ViewDelegate;
+
+#[cfg(target_os = "macos")]
+mod macos;
+
+#[cfg(target_os = "macos")]
+use macos::{register_listview_row_class, register_listview_row_class_with_delegate};
+
+#[cfg(target_os = "ios")]
+mod ios;
+
+#[cfg(target_os = "ios")]
+use ios::{register_listview_row_view_class, register_listview_row_class_with_delegate};
+
+pub(crate) static LISTVIEW_ROW_DELEGATE_PTR: &str = "rstListViewRowDelegatePtr";
+
+/// A helper method for instantiating view classes and applying default settings to them.
+fn allocate_view(registration_fn: fn() -> *const Class) -> id { 
+    unsafe {
+        let view: id = msg_send![registration_fn(), new];
+        let _: () = msg_send![view, setTranslatesAutoresizingMaskIntoConstraints:NO];
+
+        #[cfg(target_os = "macos")]
+        let _: () = msg_send![view, setWantsLayer:YES];
+
+        view 
+    }
+}
+
+/// A clone-able handler to a `ViewController` reference in the Objective C runtime. We use this
+/// instead of a stock `View` for easier recordkeeping, since it'll need to hold the `View` on that
+/// side anyway.
+#[derive(Debug)]
+pub struct ListViewRow<T = ()> {
+    /// A pointer to the Objective-C runtime view controller.
+    pub objc: ShareId<Object>,
+
+    /// A pointer to the delegate for this view.
+    pub delegate: Option<Box<T>>,
+
+    /// A pointer to the Objective-C runtime top layout constraint.
+    pub top: LayoutAnchorY,
+
+    /// A pointer to the Objective-C runtime leading layout constraint.
+    pub leading: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime trailing layout constraint.
+    pub trailing: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime bottom layout constraint.
+    pub bottom: LayoutAnchorY,
+
+    /// A pointer to the Objective-C runtime width layout constraint.
+    pub width: LayoutAnchorDimension,
+
+    /// A pointer to the Objective-C runtime height layout constraint.
+    pub height: LayoutAnchorDimension,
+
+    /// A pointer to the Objective-C runtime center X layout constraint.
+    pub center_x: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime center Y layout constraint.
+    pub center_y: LayoutAnchorY
+}
+
+impl Default for ListViewRow {
+    fn default() -> Self {
+        ListViewRow::new()
+    }
+}
+
+impl ListViewRow {
+    /// Returns a default `View`, suitable for 
+    pub fn new() -> Self {
+        let view = allocate_view(register_listview_row_class);
+
+        ListViewRow {
+            delegate: None,
+            top: LayoutAnchorY::new(unsafe { msg_send![view, topAnchor] }),
+            leading: LayoutAnchorX::new(unsafe { msg_send![view, leadingAnchor] }),
+            trailing: LayoutAnchorX::new(unsafe { msg_send![view, trailingAnchor] }),
+            bottom: LayoutAnchorY::new(unsafe { msg_send![view, bottomAnchor] }),
+            width: LayoutAnchorDimension::new(unsafe { msg_send![view, widthAnchor] }),
+            height: LayoutAnchorDimension::new(unsafe { msg_send![view, heightAnchor] }),
+            center_x: LayoutAnchorX::new(unsafe { msg_send![view, centerXAnchor] }),
+            center_y: LayoutAnchorY::new(unsafe { msg_send![view, centerYAnchor] }),
+            objc: unsafe { ShareId::from_ptr(view) },
+        }
+    }
+}
+
+impl<T> ListViewRow<T> where T: ViewDelegate + 'static {
+    /// Initializes a new View with a given `ViewDelegate`. This enables you to respond to events
+    /// and customize the view as a module, similar to class-based systems.
+    pub fn with(delegate: T) -> ListViewRow<T> {
+        let mut delegate = Box::new(delegate);
+        
+        let view = allocate_view(register_listview_row_class_with_delegate::<T>);
+        unsafe {
+            //let view: id = msg_send![register_view_class_with_delegate::<T>(), new];
+            //let _: () = msg_send![view, setTranslatesAutoresizingMaskIntoConstraints:NO];
+            let ptr: *const T = &*delegate;
+            (&mut *view).set_ivar(LISTVIEW_ROW_DELEGATE_PTR, ptr as usize);
+        };
+
+        let mut view = ListViewRow {
+            delegate: None,
+            top: LayoutAnchorY::new(unsafe { msg_send![view, topAnchor] }),
+            leading: LayoutAnchorX::new(unsafe { msg_send![view, leadingAnchor] }),
+            trailing: LayoutAnchorX::new(unsafe { msg_send![view, trailingAnchor] }),
+            bottom: LayoutAnchorY::new(unsafe { msg_send![view, bottomAnchor] }),
+            width: LayoutAnchorDimension::new(unsafe { msg_send![view, widthAnchor] }),
+            height: LayoutAnchorDimension::new(unsafe { msg_send![view, heightAnchor] }),
+            center_x: LayoutAnchorX::new(unsafe { msg_send![view, centerXAnchor] }),
+            center_y: LayoutAnchorY::new(unsafe { msg_send![view, centerYAnchor] }),
+            objc: unsafe { ShareId::from_ptr(view) },
+        };
+
+        (&mut delegate).did_load(view.clone_as_handle()); 
+        view.delegate = Some(delegate);
+        view
+    }
+}
+
+impl<T> From<&ListViewRow<T>> for ShareId<Object> {
+    fn from(row: &ListViewRow<T>) -> ShareId<Object> {
+        row.objc.clone()
+    }
+}
+
+impl<T> ListViewRow<T> {
+    /// An internal method that returns a clone of this object, sans references to the delegate or
+    /// callback pointer. We use this in calling `did_load()` - implementing delegates get a way to
+    /// reference, customize and use the view but without the trickery of holding pieces of the
+    /// delegate - the `View` is the only true holder of those.
+    pub(crate) fn clone_as_handle(&self) -> crate::view::View {
+        crate::view::View {
+            delegate: None,
+            top: self.top.clone(),
+            leading: self.leading.clone(),
+            trailing: self.trailing.clone(),
+            bottom: self.bottom.clone(),
+            width: self.width.clone(),
+            height: self.height.clone(),
+            center_x: self.center_x.clone(),
+            center_y: self.center_y.clone(),
+            objc: self.objc.clone()
+        }
+    }
+
+    /// Call this to set the background color for the backing layer.
+    pub fn set_background_color(&self, color: Color) {
+        let bg = color.into_platform_specific_color();
+        
+        unsafe {
+            let cg: id = msg_send![bg, CGColor];
+            let layer: id = msg_send![&*self.objc, layer];
+            let _: () = msg_send![layer, setBackgroundColor:cg];
+        }
+    }
+
+    /// Register this view for drag and drop operations.
+    pub fn register_for_dragged_types(&self, types: &[PasteboardType]) {
+        unsafe {
+            let types: NSArray = types.into_iter().map(|t| {
+                // This clone probably doesn't need to be here, but it should also be cheap as
+                // this is just an enum... and this is not an oft called method.
+                let x: NSString = t.clone().into();
+                x.into_inner()
+            }).collect::<Vec<id>>().into();
+
+            let _: () = msg_send![&*self.objc, registerForDraggedTypes:types.into_inner()];
+        }
+    }
+}
+
+impl<T> Layout for ListViewRow<T> {
+    fn get_backing_node(&self) -> ShareId<Object> {
+        self.objc.clone()
+    }
+
+    fn add_subview<V: Layout>(&self, view: &V) {
+        let backing_node = view.get_backing_node();
+
+        unsafe {
+            let _: () = msg_send![&*self.objc, addSubview:backing_node];
+        }
+    }
+}
+
+impl<T> Drop for ListViewRow<T> {
+    fn drop(&mut self) {
+    }
+}

src/listview/traits.rs

@@ -0,0 +1,51 @@
+//! Various traits used for Views.
+
+use crate::Node;
+use crate::dragdrop::{DragInfo, DragOperation};
+use crate::listview::{ListView, ListViewRow};
+use crate::layout::Layout;
+use crate::view::View;
+
+pub trait ListViewDelegate {
+    /// Called when the View is ready to work with. You're passed a `View` - this is safe to
+    /// store and use repeatedly, but it's not thread safe - any UI calls must be made from the
+    /// main thread!
+    fn did_load(&mut self, _view: ListView) {}
+
+    /// Returns the number of items in the list view.
+    fn number_of_items(&self) -> usize;
+
+    /// This is temporary and you should not rely on this signature if you
+    /// choose to try and work with this. NSTableView & such associated delegate patterns
+    /// are tricky to support in Rust, and while I have a few ideas about them, I haven't
+    /// had time to sit down and figure them out properly yet.
+    fn item(&self, _row: usize) -> Node;
+
+    /// Called when this is about to be added to the view heirarchy.
+    fn will_appear(&self, _animated: bool) {}
+
+    /// Called after this has been added to the view heirarchy.
+    fn did_appear(&self, _animated: bool) {}
+
+    /// Called when this is about to be removed from the view heirarchy.
+    fn will_disappear(&self, _animated: bool) {}
+
+    /// Called when this has been removed from the view heirarchy.
+    fn did_disappear(&self, _animated: bool) {}
+
+    /// Invoked when the dragged image enters destination bounds or frame; returns dragging operation to perform.
+    fn dragging_entered(&self, _info: DragInfo) -> DragOperation { DragOperation::None }
+    
+    /// Invoked when the image is released, allowing the receiver to agree to or refuse drag operation.
+    fn prepare_for_drag_operation(&self, _info: DragInfo) -> bool { false }
+
+    /// Invoked after the released image has been removed from the screen, signaling the receiver to import the pasteboard data.
+    fn perform_drag_operation(&self, _info: DragInfo) -> bool { false }
+
+    /// Invoked when the dragging operation is complete, signaling the receiver to perform any necessary clean-up.
+    fn conclude_drag_operation(&self, _info: DragInfo) {}
+
+    /// Invoked when the dragged image exits the destination’s bounds rectangle (in the case of a view) or its frame 
+    /// rectangle (in the case of a window object).
+    fn dragging_exited(&self, _info: DragInfo) {}
+}

src/macos/app/mod.rs

@@ -34,11 +34,15 @@
 //! Certain lifecycle events are specific to certain platforms. Where this is the case, the
 //! documentation makes every effort to note.
 
+use std::sync::{Arc, Mutex};
+use lazy_static::lazy_static;
+
 use objc_id::Id;
 use objc::runtime::Object;
 use objc::{class, msg_send, sel, sel_impl};
 
 use crate::foundation::{id, nil, YES, NO, NSUInteger, AutoReleasePool};
+use crate::invoker::TargetActionHandler;
 use crate::macos::menu::Menu;
 use crate::notification_center::Dispatcher;
 use crate::utils::activate_cocoa_multithreading;
@@ -57,6 +61,31 @@ pub use traits::AppDelegate;
 
 pub(crate) static APP_PTR: &str = "rstAppPtr";
 
+// Alright, so this... sucks.
+//
+// But let me explain.
+//
+// macOS only has one top level menu, and it's probably one of the old(est|er)
+// parts of the system - there's still Carbon there, if you know where to look.
+// We store our event handlers on the Rust side, and in most cases this works fine - 
+// we can enforce that the programmer should be retaining ownership and dropping
+// when ready.
+//
+// We can't enforce this with NSMenu, as it takes ownership of the items and then
+// lives in its own world. We want to mirror the same contract, somehow... so, again,
+// we go back to the "one top level menu" bit.
+//
+// Yes, all this to say, this is a singleton that caches TargetActionHandler entries
+// when menus are constructed. It's mostly 1:1 with the NSMenu, I think - and probably
+// the only true singleton I want to see in this framework.
+//
+// Calls to App::set_menu() will reconfigure the contents of this Vec, so that's also
+// the easiest way to remove things as necessary - just rebuild your menu. Trying to debug
+// and/or predict NSMenu is a whole task that I'm not even sure is worth trying to do.
+lazy_static! {
+    static ref MENU_ITEMS_HANDLER_CACHE: Arc<Mutex<Vec<TargetActionHandler>>> = Arc::new(Mutex::new(Vec::new()));
+}
+
 /// A handler to make some boilerplate less annoying.
 #[inline]
 fn shared_application<F: Fn(id)>(handler: F) {
@@ -91,7 +120,6 @@ impl<T> App<T> {
     pub fn run(&self) {
         unsafe {
             let current_app: id = msg_send![class!(NSRunningApplication), currentApplication];
-            let _: () = msg_send![current_app, activateWithOptions:1<<1];
             let shared_app: id = msg_send![class!(RSTApplication), sharedApplication];
             let _: () = msg_send![shared_app, run];
             self.pool.drain();
@@ -112,7 +140,6 @@ impl<T> App<T> where T: AppDelegate + 'static {
 
         let inner = unsafe {
             let app: id = msg_send![register_app_class(), sharedApplication];
-            let _: () = msg_send![app, setActivationPolicy:0];
             Id::from_ptr(app)
         };
         
@@ -137,11 +164,25 @@ impl<T> App<T> where T: AppDelegate + 'static {
     }
 } 
 
-// This is a hack and should be replaced with an actual messaging pipeline at some point. :)
+//  This is a very basic "dispatch" mechanism. In macOS, it's critical that UI work happen on the
+//  UI ("main") thread. We can hook into the standard mechanism for this by dispatching on
+//  queues; in our case, we'll just offer two points - one for the background queue(s), and one
+//  for the main queue. They automatically forward through to our registered `AppDelegate`.
+//
+//  One thing I don't like about GCD is that detecting incorrect thread usage has historically been
+//  a bit... annoying. Here, the `Dispatcher` trait explicitly requires implementing two methods - 
+//  one for UI messages, and one for background messages. I think that this helps separate intent
+//  on the implementation side, and makes it a bit easier to detect when a message has come in on
+//  the wrong side.
+//
+//  This is definitely, absolutely, 100% not a performant way to do things - but at the same time,
+//  ObjC and such is fast enough that for a large class of applications this is workable.
+//
+//  tl;dr: This is all a bit of a hack, and should go away eventually. :)
 impl<T, M> App<T, M> where M: Send + Sync + 'static, T: AppDelegate + Dispatcher<Message = M> {
     /// Dispatches a message by grabbing the `sharedApplication`, getting ahold of the delegate,
-    /// and passing back through there. All messages are currently dispatched on the main thread.
-    pub fn dispatch(message: M) {
+    /// and passing back through there.
+    pub fn dispatch_main(message: M) {
         let queue = dispatch::Queue::main();
         
         queue.exec_async(move || unsafe {
@@ -149,7 +190,21 @@ impl<T, M> App<T, M> where M: Send + Sync + 'static, T: AppDelegate + Dispatcher
             let app_delegate: id = msg_send![app, delegate];
             let delegate_ptr: usize = *(*app_delegate).get_ivar(APP_PTR);
             let delegate = delegate_ptr as *const T;
-            (&*delegate).on_message(message);
+            (&*delegate).on_ui_message(message);
+        });
+    }
+
+    /// Dispatches a message by grabbing the `sharedApplication`, getting ahold of the delegate,
+    /// and passing back through there.
+    pub fn dispatch_background(message: M) {
+        let queue = dispatch::Queue::main();
+        
+        queue.exec_async(move || unsafe {
+            let app: id = msg_send![register_app_class(), sharedApplication];
+            let app_delegate: id = msg_send![app, delegate];
+            let delegate_ptr: usize = *(*app_delegate).get_ivar(APP_PTR);
+            let delegate = delegate_ptr as *const T;
+            (&*delegate).on_background_message(message);
         });
     }
 }
@@ -202,22 +257,54 @@ impl App {
     /// Sets a set of `Menu`'s as the top level Menu for the current application. Note that behind
     /// the scenes, Cocoa/AppKit make a copy of the menu you pass in - so we don't retain it, and
     /// you shouldn't bother to either.
-    pub fn set_menu(menus: Vec<Menu>) {
-        shared_application(|app| unsafe {
+    ///
+    /// The one note here: we internally cache actions to avoid them dropping without the
+    /// Objective-C side knowing. The the comments on the 
+    pub fn set_menu(mut menus: Vec<Menu>) {
+        let mut handlers = vec![];
+        
+        let main_menu = unsafe {
             let menu_cls = class!(NSMenu);
+            let item_cls = class!(NSMenuItem);
             let main_menu: id = msg_send![menu_cls, new];
 
-            let item_cls = class!(NSMenuItem);
-            for menu in menus.iter() {
+            for menu in menus.iter_mut() {
+                handlers.append(&mut menu.actions);
+
                 let item: id = msg_send![item_cls, new];
                 let _: () = msg_send![item, setSubmenu:&*menu.inner];
                 let _: () = msg_send![main_menu, addItem:item];
             }
 
+            main_menu
+        };
+
+        // Cache our menu handlers, whatever they may be - since we're replacing the
+        // existing menu, and macOS only has one menu on screen at a time, we can go
+        // ahead and blow away the old ones.
+        {
+            let mut cache = MENU_ITEMS_HANDLER_CACHE.lock().unwrap();
+            *cache = handlers;
+        }
+
+        shared_application(move |app| unsafe {
             let _: () = msg_send![app, setMainMenu:main_menu];
         });
     }
 
+    /// For nib-less applications (which, if you're here, this is) need to call the activation
+    /// routines after the NSMenu has been set, otherwise it won't be interact-able without
+    /// switching away from the app and then coming back.
+    ///
+    /// @TODO: Accept an ActivationPolicy enum or something.
+    pub fn activate() {
+        shared_application(|app| unsafe {
+            let _: () = msg_send![app, setActivationPolicy:0];
+            let current_app: id = msg_send![class!(NSRunningApplication), currentApplication];
+            let _: () = msg_send![current_app, activateWithOptions:1<<1];
+        });
+    }
+
     /// Terminates the application, firing the requisite cleanup delegate methods in the process.
     ///
     /// This is typically called when the user chooses to quit via the App menu.

src/macos/menu/item.rs

@@ -5,9 +5,11 @@
 use objc::{class, msg_send, sel, sel_impl};
 use objc::runtime::{Object, Sel};
 use objc_id::ShareId;
+use std::sync::Once;
 
 use crate::foundation::{id, nil, NSString, NSUInteger};
 use crate::events::EventModifierFlag;
+use crate::invoker::TargetActionHandler;
 
 /// Internal method (shorthand) for generating `NSMenuItem` holders.
 fn make_menu_item(
@@ -17,8 +19,6 @@ fn make_menu_item(
     modifiers: Option<&[EventModifierFlag]>
 ) -> MenuItem {
     unsafe {
-        let cls = class!(NSMenuItem);
-        let alloc: id = msg_send![cls, alloc];
         let title = NSString::new(title);
 
         // Note that AppKit requires a blank string if nil, not nil.
@@ -27,6 +27,7 @@ fn make_menu_item(
             None => ""
         });
 
+        let alloc: id = msg_send![class!(NSMenuItem), alloc];
         let item = ShareId::from_ptr(match action {
             Some(a) => msg_send![alloc, initWithTitle:title action:a keyEquivalent:key],
             None => msg_send![alloc, initWithTitle:title action:nil keyEquivalent:key]
@@ -43,7 +44,7 @@ fn make_menu_item(
             let _: () = msg_send![&*item, setKeyEquivalentModifierMask:key_mask];
         }
 
-        MenuItem::Action(item)
+        MenuItem::Entry((item, None))
     }
 }
 
@@ -52,7 +53,7 @@ fn make_menu_item(
 pub enum MenuItem {
     /// Represents a Menu item that's not a separator - for all intents and purposes, you can consider
     /// this the real `NSMenuItem`.
-    Action(ShareId<Object>),
+    Entry((ShareId<Object>, Option<TargetActionHandler>)),
 
     /// Represents a Separator. You can't do anything with this, but it's useful nonetheless for
     /// separating out pieces of the `NSMenu` structure.
@@ -60,8 +61,8 @@ pub enum MenuItem {
 }
 
 impl MenuItem {
-    /// Creates and returns a `MenuItem::Action` with the specified title.
-    pub fn action(title: &str) -> Self {
+    /// Creates and returns a `MenuItem::Entry` with the specified title.
+    pub fn entry(title: &str) -> Self {
         make_menu_item(title, None, None, None)
     }
 
@@ -70,13 +71,25 @@ impl MenuItem {
         match self {
             MenuItem::Separator => MenuItem::Separator,
 
-            MenuItem::Action(item) => {
+            MenuItem::Entry((item, action)) => {
                 unsafe {
                     let key = NSString::new(key);
                     let _: () = msg_send![&*item, setKeyEquivalent:key];
                 }
 
-                MenuItem::Action(item)
+                MenuItem::Entry((item, action))
+            }
+        }
+    }
+
+    /// Attaches a target/action handler to dispatch events.
+    pub fn action<F: Fn() + Send + Sync + 'static>(self, action: F) -> Self {
+        match self {
+            MenuItem::Separator => MenuItem::Separator,
+
+            MenuItem::Entry((item, old_action)) => {
+                let action = TargetActionHandler::new(&*item, action);
+                MenuItem::Entry((item, Some(action)))
             }
         }        
     }
@@ -97,14 +110,14 @@ impl MenuItem {
     pub fn services() -> Self {
         match make_menu_item("Services", None, None, None) {
             // Link in the services menu, which is part of NSApp
-            MenuItem::Action(item) => {
+            MenuItem::Entry((item, action)) => {
                 unsafe {
                     let app: id = msg_send![class!(RSTApplication), sharedApplication];
                     let services: id = msg_send![app, servicesMenu];
                     let _: () = msg_send![&*item, setSubmenu:services];
                 }
 
-                MenuItem::Action(item)
+                MenuItem::Entry((item, action))
             },
 
             // Should never be hit

src/macos/menu/menu.rs

@@ -1,22 +1,33 @@
 //! Wraps NSMenu and handles instrumenting necessary delegate pieces.
 
-use objc_id::Id;
+use std::sync::{Arc, Mutex};
+
+use objc_id::{Id, ShareId};
 use objc::runtime::Object;
 use objc::{class, msg_send, sel, sel_impl};
 
 use crate::foundation::{id, NSString};
 use crate::macos::menu::item::MenuItem;
+use crate::invoker::TargetActionHandler;
 
 /// A struct that represents an `NSMenu`. It takes ownership of items, and handles instrumenting
 /// them throughout the application lifecycle.
 #[derive(Debug)]
 pub struct Menu {
     pub inner: Id<Object>,
-    pub items: Vec<MenuItem>
+    pub actions: Vec<TargetActionHandler>
 }
 
 impl Menu {
     /// Creates a new `Menu` with the given title, and uses the passed items as submenu items.
+    ///
+    /// This method effectively does three things:
+    ///
+    ///     - Consumes the MenuItem Vec, and pulls out handlers we need to cache
+    ///     - Configures the menu items appropriately, and wires them up
+    ///     - Drops the values we no longer need, and returns only what's necessary
+    ///         to get the menu functioning.
+    ///
     pub fn new(title: &str, items: Vec<MenuItem>) -> Self {
         let inner = unsafe {
             let cls = class!(NSMenu);
@@ -26,11 +37,17 @@ impl Menu {
             Id::from_ptr(inner)
         };
 
-        for item in items.iter() {
+        let mut actions = vec![];
+
+        for item in items {
             match item {
-                MenuItem::Action(item) => {
+                MenuItem::Entry((item, action)) => {
                     unsafe {
-                        let _: () = msg_send![&*inner, addItem:item.clone()];
+                        let _: () = msg_send![&*inner, addItem:item];
+                    }
+
+                    if action.is_some() {
+                        actions.push(action.unwrap());
                     }
                 },
 
@@ -46,7 +63,7 @@ impl Menu {
 
         Menu {
             inner: inner,
-            items: items
+            actions: actions
         }
     }
 }

src/macos/toolbar/class.rs

@@ -4,7 +4,7 @@ use std::sync::Once;
 
 use objc::declare::ClassDecl;
 use objc::runtime::{Class, Object, Sel};
-use objc::{class, sel, sel_impl};
+use objc::{class, sel, sel_impl, msg_send};
 
 use crate::foundation::{id, NSArray, NSString};
 use crate::macos::toolbar::{TOOLBAR_PTR, ToolbarDelegate};
@@ -38,8 +38,11 @@ extern fn item_for_identifier<T: ToolbarDelegate>(this: &Object, _: Sel, _: id,
     let toolbar = load::<T>(this, TOOLBAR_PTR);
     let identifier = NSString::wrap(identifier);
     
-    let mut item = toolbar.item_for(identifier.to_str());
-    &mut *item.objc
+    let item = toolbar.item_for(identifier.to_str());
+    unsafe {
+        msg_send![&*item.objc, self]
+    }
+    //&mut *item.objc
 }
 
 /// Registers a `NSToolbar` subclass, and configures it to hold some ivars for various things we need

src/macos/toolbar/item.rs

@@ -3,20 +3,24 @@
 //!
 //! UNFORTUNATELY, this is a very old and janky API. So... yeah.
 
+use std::fmt;
 use core_graphics::geometry::CGSize;
 
-use objc_id::Id;
-use objc::runtime::Object;
+use objc_id::{Id, ShareId};
+use objc::runtime::{Object};
 use objc::{class, msg_send, sel, sel_impl};
 
 use crate::foundation::{id, NSString};
+use crate::invoker::TargetActionHandler;
 use crate::button::Button;
 
 /// Wraps `NSToolbarItem`. Enables configuring things like size, view, and so on.
+#[derive(Debug)]
 pub struct ToolbarItem {
     pub identifier: String,
     pub objc: Id<Object>,
-    pub button: Option<Button>
+    pub button: Option<Button>,
+    handler: Option<TargetActionHandler>
 }
 
 impl ToolbarItem {
@@ -35,15 +39,17 @@ impl ToolbarItem {
         ToolbarItem {
             identifier: identifier,
             objc: objc,
-            button: None
+            button: None,
+            handler: None
         }
     }
 
     /// Sets the title for this item.
     pub fn set_title(&mut self, title: &str) {
         unsafe {
-            let title = NSString::new(title);
-            let _: () = msg_send![&*self.objc, setTitle:title];
+            let title = NSString::new(title).into_inner();
+            let _: () = msg_send![&*self.objc, setLabel:&*title];
+            let _: () = msg_send![&*self.objc, setTitle:&*title];
         }
     }
 
@@ -73,4 +79,9 @@ impl ToolbarItem {
             let _: () = msg_send![&*self.objc, setMaxSize:size];
         }
     }
+
+    pub fn set_action<F: Fn() + Send + Sync + 'static>(&mut self, action: F) {
+        let handler = TargetActionHandler::new(&*self.objc, action);
+        self.handler = Some(handler);
+    }
 }

src/macos/toolbar/traits.rs

@@ -18,5 +18,5 @@ pub trait ToolbarDelegate {
     fn default_item_identifiers(&self) -> Vec<&'static str>;
 
     /// For a given `identifier`, return the `ToolbarItem` that should be displayed.
-    fn item_for(&self, _identifier: &str) -> ToolbarItem;
+    fn item_for(&self, _identifier: &str) -> &ToolbarItem;
 }

src/macos/window/mod.rs

@@ -137,6 +137,8 @@ impl<T> Window<T> where T: WindowDelegate + 'static {
             // We set the window to be its own delegate - this is cleaned up inside `Drop`.
             let _: () = msg_send![window, setDelegate:window];
 
+            let _: () = msg_send![window, setRestorable:NO];
+
             ShareId::from_ptr(window)
         };
 

src/notification_center/traits.rs

@@ -1,8 +1,7 @@
-
-/// Controllers interested in processing messages can implement this to respond to messages as
-/// they're dispatched. All messages come in on the main thread.
 pub trait Dispatcher {
     type Message: Send + Sync;
 
-    fn on_message(&self, _message: Self::Message) {}
+    fn on_ui_message(&self, _message: Self::Message) {}
+
+    fn on_background_message(&self, _message: Self::Message) {}
 }

src/pasteboard/mod.rs

@@ -4,7 +4,7 @@
 
 use objc::runtime::Object;
 use objc::{class, msg_send, sel, sel_impl};
-use objc_id::Id;
+use objc_id::ShareId;
 use url::Url;
 
 use crate::foundation::{id, nil, NSString, NSArray};
@@ -14,12 +14,12 @@ mod types;
 pub use types::{PasteboardName, PasteboardType};
 
 /// Represents an `NSPasteboard`, enabling you to handle copy/paste/drag and drop.
-pub struct Pasteboard(pub Id<Object>);
+pub struct Pasteboard(pub ShareId<Object>);
 
 impl Default for Pasteboard {
     fn default() -> Self {
         Pasteboard(unsafe {
-            Id::from_retained_ptr(msg_send![class!(NSPasteboard), generalPasteboard])
+            ShareId::from_ptr(msg_send![class!(NSPasteboard), generalPasteboard])
         })
     }
 }
@@ -28,7 +28,7 @@ impl Pasteboard {
     /// Used internally for wrapping a Pasteboard returned from operations (say, drag and drop).
     pub(crate) fn with(existing: id) -> Self {
         Pasteboard(unsafe {
-            Id::from_retained_ptr(existing)
+            ShareId::from_ptr(existing)
         })
     }
 
@@ -36,7 +36,7 @@ impl Pasteboard {
     pub fn named(name: PasteboardName) -> Self {
         Pasteboard(unsafe {
             let name: NSString = name.into();
-            Id::from_retained_ptr(msg_send![class!(NSPasteboard), pasteboardWithName:&*name.0])
+            ShareId::from_ptr(msg_send![class!(NSPasteboard), pasteboardWithName:&*name.0])
         })
     }
 
@@ -44,7 +44,7 @@ impl Pasteboard {
     /// respect to other pasteboards in the system.
     pub fn unique() -> Self {
         Pasteboard(unsafe {
-            Id::from_ptr(msg_send![class!(NSPasteboard), pasteboardWithUniqueName])
+            ShareId::from_ptr(msg_send![class!(NSPasteboard), pasteboardWithUniqueName])
         })
     }
 

src/quicklook/config.rs

@@ -0,0 +1,102 @@
+use core_graphics::base::CGFloat;
+use objc::runtime::{Object};
+use objc::{class, msg_send, sel, sel_impl};
+use objc_id::ShareId;
+
+use url::Url;
+
+use crate::foundation::{id, YES, NSString, NSUInteger};
+use crate::utils::CGSize;
+
+/// Describes the quality of the thumbnail you expect back from the 
+/// generator service.
+#[derive(Debug)]
+pub enum ThumbnailQuality {
+    /// Appropriate for a file icon.
+    Icon,
+
+    /// Low-ish quality, but fast.
+    Low,
+
+    /// Higher quality, but potentially slower.
+    High,
+
+    /// Ask for them all, and pick which one you
+    /// use via your provided callback.
+    All
+}
+
+impl From<&ThumbnailQuality> for NSUInteger {
+    fn from(quality: &ThumbnailQuality) -> Self {
+        match quality {
+            ThumbnailQuality::Icon => 1 << 0,
+            ThumbnailQuality::Low => 1 << 1,
+            ThumbnailQuality::High => 1 << 2,
+            ThumbnailQuality::All => NSUInteger::MAX
+        }
+    }
+}
+
+
+#[derive(Clone, Debug)]
+pub struct ThumbnailConfig {
+    pub size: (CGFloat, CGFloat),
+    pub scale: CGFloat,
+    pub minimum_dimension: CGFloat,
+    pub icon_mode: bool,
+    pub types: &'static [ThumbnailQuality]
+}
+
+impl Default for ThumbnailConfig {
+    fn default() -> Self {
+        ThumbnailConfig {
+            size: (44., 44.),
+            
+            // #TODO: Should query the current screen size maybe? 2x is fairly safe
+            // for most moderns Macs right now.
+            scale: 2.,
+            
+            minimum_dimension: 0.,
+
+            icon_mode: false,
+
+            types: &[ThumbnailQuality::All]
+        }
+    }
+}
+
+impl ThumbnailConfig {
+    /// Consumes the request and returns a native representation 
+    /// (`QLThumbnailGenerationRequest`).
+    pub fn to_request(self, url: &Url) -> id {
+        let file = NSString::new(url.as_str());
+
+        let mut types: NSUInteger = 0;
+        for mask in self.types {
+            let i: NSUInteger = mask.into();
+            types = types | i;
+        }
+
+        unsafe {
+            let size = CGSize::new(self.size.0, self.size.1);
+            let from_url: id = msg_send![class!(NSURL), URLWithString:file.into_inner()];
+
+
+            let request: id = msg_send![class!(QLThumbnailGenerationRequest), alloc];
+            let request: id = msg_send![request, initWithFileAtURL:from_url
+                size:size
+                scale:self.scale
+                representationTypes:types];
+
+            if self.icon_mode {
+                let _: () = msg_send![request, setIconMode:YES];
+            }
+
+            if self.minimum_dimension != 0. {
+                let _: () = msg_send![request, setMinimumDimension:self.minimum_dimension];
+            }
+
+            request
+        }
+    }
+}

src/quicklook/mod.rs

@@ -0,0 +1,46 @@
+use objc::runtime::{Object};
+use objc::{class, msg_send, sel, sel_impl};
+use objc_id::ShareId;
+
+use block::ConcreteBlock;
+
+use url::Url;
+
+use crate::error::Error;
+use crate::foundation::{id, NSUInteger};
+use crate::image::Image;
+
+mod config;
+pub use config::{ThumbnailConfig, ThumbnailQuality};
+
+#[derive(Debug)]
+pub struct ThumbnailGenerator(pub ShareId<Object>);
+
+impl ThumbnailGenerator {
+    pub fn shared() -> Self {
+        ThumbnailGenerator(unsafe {
+            ShareId::from_ptr(msg_send![class!(QLThumbnailGenerator), sharedGenerator])
+        })
+    }
+
+    pub fn generate<F>(&self, url: &Url, config: ThumbnailConfig, callback: F)
+    where
+        //F: Fn(Result<(Image, ThumbnailQuality), Error>) + Send + Sync + 'static
+        F: Fn(Result<(Image, ThumbnailQuality), Error>) + Send + Sync + 'static
+    {
+        let block = ConcreteBlock::new(move |thumbnail: id, thumbnail_type: NSUInteger, error: id| {
+            unsafe {
+                let image = Image::with(msg_send![thumbnail, NSImage]);
+                callback(Ok((image, ThumbnailQuality::Low)));
+            }
+        });
+
+        let block = block.copy();
+        let request = config.to_request(url);
+
+        unsafe {
+            let _: () = msg_send![&*self.0, generateRepresentationsForRequest:request 
+                updateHandler:block];
+        }
+    }
+}

src/scrollview/macos.rs

@@ -0,0 +1,120 @@
+//! This module does one specific thing: register a custom `NSView` class that's... brought to the
+//! modern era.
+//!
+//! I kid, I kid.
+//!
+//! It just enforces that coordinates are judged from the top-left, which is what most people look
+//! for in the modern era. It also implements a few helpers for things like setting a background
+//! color, and enforcing layer backing by default.
+
+use std::sync::Once;
+
+use objc::declare::ClassDecl;
+use objc::runtime::{Class, Object, Sel, BOOL};
+use objc::{class, sel, sel_impl};
+use objc_id::Id;
+
+use crate::foundation::{id, YES, NO, NSUInteger};
+use crate::dragdrop::DragInfo;
+use crate::scrollview::{SCROLLVIEW_DELEGATE_PTR, ScrollViewDelegate};
+use crate::utils::load;
+
+/// Enforces normalcy, or: a needlessly cruel method in terms of the name. You get the idea though.
+extern fn enforce_normalcy(_: &Object, _: Sel) -> BOOL {
+    return YES;
+}
+
+/// Called when a drag/drop operation has entered this view.
+extern fn dragging_entered<T: ScrollViewDelegate>(this: &mut Object, _: Sel, info: id) -> NSUInteger {
+    let view = load::<T>(this, SCROLLVIEW_DELEGATE_PTR);
+    view.dragging_entered(DragInfo {
+        info: unsafe { Id::from_ptr(info) }
+    }).into()
+}
+
+/// Called when a drag/drop operation has entered this view.
+extern fn prepare_for_drag_operation<T: ScrollViewDelegate>(this: &mut Object, _: Sel, info: id) -> BOOL {
+    let view = load::<T>(this, SCROLLVIEW_DELEGATE_PTR);
+    
+    match view.prepare_for_drag_operation(DragInfo {
+        info: unsafe { Id::from_ptr(info) }
+    }) {
+        true => YES,
+        false => NO
+    }
+}
+
+/// Called when a drag/drop operation has entered this view.
+extern fn perform_drag_operation<T: ScrollViewDelegate>(this: &mut Object, _: Sel, info: id) -> BOOL {
+    let view = load::<T>(this, SCROLLVIEW_DELEGATE_PTR);
+        
+    match view.perform_drag_operation(DragInfo {
+        info: unsafe { Id::from_ptr(info) }
+    }) {
+        true => YES,
+        false => NO
+    }
+}
+
+/// Called when a drag/drop operation has entered this view.
+extern fn conclude_drag_operation<T: ScrollViewDelegate>(this: &mut Object, _: Sel, info: id) {
+    let view = load::<T>(this, SCROLLVIEW_DELEGATE_PTR);
+    
+    view.conclude_drag_operation(DragInfo {
+        info: unsafe { Id::from_ptr(info) }
+    });           
+}
+
+/// Called when a drag/drop operation has entered this view.
+extern fn dragging_exited<T: ScrollViewDelegate>(this: &mut Object, _: Sel, info: id) {
+    let view = load::<T>(this, SCROLLVIEW_DELEGATE_PTR);
+        
+    view.dragging_exited(DragInfo {
+        info: unsafe { Id::from_ptr(info) }
+    });
+}
+
+/// Injects an `NSScrollView` subclass. 
+pub(crate) fn register_scrollview_class() -> *const Class {
+    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    static INIT: Once = Once::new();
+
+    INIT.call_once(|| unsafe {
+        let superclass = class!(NSScrollView);
+        let mut decl = ClassDecl::new("RSTScrollView", superclass).unwrap();
+        VIEW_CLASS = decl.register();
+    });
+
+    unsafe { VIEW_CLASS }
+}
+
+/// Injects an `NSView` subclass, with some callback and pointer ivars for what we
+/// need to do.
+pub(crate) fn register_scrollview_class_with_delegate<T: ScrollViewDelegate>() -> *const Class {
+    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    static INIT: Once = Once::new();
+
+    INIT.call_once(|| unsafe {
+        let superclass = class!(NSScrollView);
+        let mut decl = ClassDecl::new("RSTScrollViewWithDelegate", superclass).unwrap();
+
+        // A pointer to the "view controller" on the Rust side. It's expected that this doesn't
+        // move.
+        decl.add_ivar::<usize>(SCROLLVIEW_DELEGATE_PTR);
+        
+        decl.add_method(sel!(isFlipped), enforce_normalcy as extern fn(&Object, _) -> BOOL);
+
+        // Drag and drop operations (e.g, accepting files)
+        decl.add_method(sel!(draggingEntered:), dragging_entered::<T> as extern fn (&mut Object, _, _) -> NSUInteger);
+        decl.add_method(sel!(prepareForDragOperation:), prepare_for_drag_operation::<T> as extern fn (&mut Object, _, _) -> BOOL);
+        decl.add_method(sel!(performDragOperation:), perform_drag_operation::<T> as extern fn (&mut Object, _, _) -> BOOL);
+        decl.add_method(sel!(concludeDragOperation:), conclude_drag_operation::<T> as extern fn (&mut Object, _, _));
+        decl.add_method(sel!(draggingExited:), dragging_exited::<T> as extern fn (&mut Object, _, _));
+        
+        VIEW_CLASS = decl.register();
+    });
+
+    unsafe {
+        VIEW_CLASS
+    }
+}

src/scrollview/mod.rs

@@ -0,0 +1,245 @@
+//! Wraps `NSView` and `UIView` across platforms.
+//!
+//! This implementation errs towards the `UIView` side of things, and mostly acts as a wrapper to
+//! bring `NSView` to the modern era. It does this by flipping the coordinate system to be what
+//! people expect in 2020, and layer-backing all views by default.
+//!
+//! Views implement Autolayout, which enable you to specify how things should appear on the screen.
+//! 
+//! ```rust,no_run
+//! use cacao::color::rgb;
+//! use cacao::layout::{Layout, LayoutConstraint};
+//! use cacao::view::View;
+//! use cacao::window::{Window, WindowDelegate};
+//!
+//! #[derive(Default)]
+//! struct AppWindow {
+//!     content: View,
+//!     red: View,
+//!     window: Window
+//! }
+//! 
+//! impl WindowDelegate for AppWindow {
+//!     fn did_load(&mut self, window: Window) {
+//!         window.set_minimum_content_size(300., 300.);
+//!         self.window = window;
+//!
+//!         self.red.set_background_color(rgb(224, 82, 99));
+//!         self.content.add_subview(&self.red);
+//!         
+//!         self.window.set_content_view(&self.content);
+//!
+//!         LayoutConstraint::activate(&[
+//!             self.red.top.constraint_equal_to(&self.content.top).offset(16.),
+//!             self.red.leading.constraint_equal_to(&self.content.leading).offset(16.),
+//!             self.red.trailing.constraint_equal_to(&self.content.trailing).offset(-16.),
+//!             self.red.bottom.constraint_equal_to(&self.content.bottom).offset(-16.),
+//!         ]);
+//!     }
+//! }
+//! ```
+//!
+//! For more information on Autolayout, view the module or check out the examples folder.
+
+use objc_id::ShareId;
+use objc::runtime::{Class, Object};
+use objc::{msg_send, sel, sel_impl};
+
+use crate::foundation::{id, nil, YES, NO, NSArray, NSString};
+use crate::color::Color;
+use crate::layout::{Layout, LayoutAnchorX, LayoutAnchorY, LayoutAnchorDimension};
+use crate::pasteboard::PasteboardType;
+
+#[cfg(target_os = "macos")]
+mod macos;
+
+#[cfg(target_os = "macos")]
+use macos::{register_scrollview_class, register_scrollview_class_with_delegate};
+
+#[cfg(target_os = "ios")]
+mod ios;
+
+#[cfg(target_os = "ios")]
+use ios::{register_view_class, register_view_class_with_delegate};
+
+mod traits;
+pub use traits::ScrollViewDelegate;
+
+pub(crate) static SCROLLVIEW_DELEGATE_PTR: &str = "rstScrollViewDelegatePtr";
+
+/// A helper method for instantiating view classes and applying default settings to them.
+fn allocate_view(registration_fn: fn() -> *const Class) -> id { 
+    unsafe {
+        let view: id = msg_send![registration_fn(), new];
+        let _: () = msg_send![view, setTranslatesAutoresizingMaskIntoConstraints:NO];
+
+        #[cfg(target_os = "macos")]
+        {
+            let _: () = msg_send![view, setDrawsBackground:NO];
+            let _: () = msg_send![view, setWantsLayer:YES];
+            let _: () = msg_send![view, setBorderType:0];
+            let _: () = msg_send![view, setHorizontalScrollElasticity:1];
+            let _: () = msg_send![view, setHasVerticalScroller:YES];
+        }
+
+        view 
+    }
+}
+
+/// A clone-able handler to a `NS/UIScrollView` reference in the Objective C runtime.
+#[derive(Debug)]
+pub struct ScrollView<T = ()> {
+    /// A pointer to the Objective-C runtime view controller.
+    pub objc: ShareId<Object>,
+
+    /// A pointer to the delegate for this view.
+    pub delegate: Option<Box<T>>,
+
+    /// A pointer to the Objective-C runtime top layout constraint.
+    pub top: LayoutAnchorY,
+
+    /// A pointer to the Objective-C runtime leading layout constraint.
+    pub leading: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime trailing layout constraint.
+    pub trailing: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime bottom layout constraint.
+    pub bottom: LayoutAnchorY,
+
+    /// A pointer to the Objective-C runtime width layout constraint.
+    pub width: LayoutAnchorDimension,
+
+    /// A pointer to the Objective-C runtime height layout constraint.
+    pub height: LayoutAnchorDimension,
+
+    /// A pointer to the Objective-C runtime center X layout constraint.
+    pub center_x: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime center Y layout constraint.
+    pub center_y: LayoutAnchorY
+}
+
+impl Default for ScrollView {
+    fn default() -> Self {
+        ScrollView::new()
+    }
+}
+
+impl ScrollView {
+    /// Returns a default `View`, suitable for 
+    pub fn new() -> Self {
+        let view = allocate_view(register_scrollview_class);
+
+        ScrollView {
+            delegate: None,
+            top: LayoutAnchorY::new(unsafe { msg_send![view, topAnchor] }),
+            leading: LayoutAnchorX::new(unsafe { msg_send![view, leadingAnchor] }),
+            trailing: LayoutAnchorX::new(unsafe { msg_send![view, trailingAnchor] }),
+            bottom: LayoutAnchorY::new(unsafe { msg_send![view, bottomAnchor] }),
+            width: LayoutAnchorDimension::new(unsafe { msg_send![view, widthAnchor] }),
+            height: LayoutAnchorDimension::new(unsafe { msg_send![view, heightAnchor] }),
+            center_x: LayoutAnchorX::new(unsafe { msg_send![view, centerXAnchor] }),
+            center_y: LayoutAnchorY::new(unsafe { msg_send![view, centerYAnchor] }),
+            objc: unsafe { ShareId::from_ptr(view) },
+        }
+    }
+}
+
+impl<T> ScrollView<T> where T: ScrollViewDelegate + 'static {
+    /// Initializes a new View with a given `ViewDelegate`. This enables you to respond to events
+    /// and customize the view as a module, similar to class-based systems.
+    pub fn with(delegate: T) -> ScrollView<T> {
+        let mut delegate = Box::new(delegate);
+        
+        let view = allocate_view(register_scrollview_class_with_delegate::<T>);
+        unsafe {
+            //let view: id = msg_send![register_view_class_with_delegate::<T>(), new];
+            //let _: () = msg_send![view, setTranslatesAutoresizingMaskIntoConstraints:NO];
+            let ptr: *const T = &*delegate;
+            (&mut *view).set_ivar(SCROLLVIEW_DELEGATE_PTR, ptr as usize);
+        };
+
+        let mut view = ScrollView {
+            delegate: None,
+            top: LayoutAnchorY::new(unsafe { msg_send![view, topAnchor] }),
+            leading: LayoutAnchorX::new(unsafe { msg_send![view, leadingAnchor] }),
+            trailing: LayoutAnchorX::new(unsafe { msg_send![view, trailingAnchor] }),
+            bottom: LayoutAnchorY::new(unsafe { msg_send![view, bottomAnchor] }),
+            width: LayoutAnchorDimension::new(unsafe { msg_send![view, widthAnchor] }),
+            height: LayoutAnchorDimension::new(unsafe { msg_send![view, heightAnchor] }),
+            center_x: LayoutAnchorX::new(unsafe { msg_send![view, centerXAnchor] }),
+            center_y: LayoutAnchorY::new(unsafe { msg_send![view, centerYAnchor] }),
+            objc: unsafe { ShareId::from_ptr(view) },
+        };
+
+        (&mut delegate).did_load(view.clone_as_handle()); 
+        view.delegate = Some(delegate);
+        view
+    }
+}
+
+impl<T> ScrollView<T> {
+    /// An internal method that returns a clone of this object, sans references to the delegate or
+    /// callback pointer. We use this in calling `did_load()` - implementing delegates get a way to
+    /// reference, customize and use the view but without the trickery of holding pieces of the
+    /// delegate - the `View` is the only true holder of those.
+    pub(crate) fn clone_as_handle(&self) -> ScrollView {
+        ScrollView {
+            delegate: None,
+            top: self.top.clone(),
+            leading: self.leading.clone(),
+            trailing: self.trailing.clone(),
+            bottom: self.bottom.clone(),
+            width: self.width.clone(),
+            height: self.height.clone(),
+            center_x: self.center_x.clone(),
+            center_y: self.center_y.clone(),
+            objc: self.objc.clone()
+        }
+    }
+
+    /// Call this to set the background color for the backing layer.
+    pub fn set_background_color(&self, color: Color) {
+        let bg = color.into_platform_specific_color();
+        
+        unsafe {
+            let cg: id = msg_send![bg, CGColor];
+            let layer: id = msg_send![&*self.objc, layer];
+            let _: () = msg_send![layer, setBackgroundColor:cg];
+        }
+    }
+}
+
+impl<T> Layout for ScrollView<T> {
+    fn get_backing_node(&self) -> ShareId<Object> {
+        self.objc.clone()
+    }
+
+    fn add_subview<V: Layout>(&self, view: &V) {
+        let backing_node = view.get_backing_node();
+
+        unsafe {
+            let _: () = msg_send![&*self.objc, addSubview:backing_node];
+        }
+    }
+}
+
+impl<T> Drop for ScrollView<T> {
+    /// A bit of extra cleanup for delegate callback pointers. If the originating `View` is being
+    /// dropped, we do some logic to clean it all up (e.g, we go ahead and check to see if
+    /// this has a superview (i.e, it's in the heirarchy) on the AppKit side. If it does, we go
+    /// ahead and remove it - this is intended to match the semantics of how Rust handles things).
+    ///
+    /// There are, thankfully, no delegates we need to break here.
+    fn drop(&mut self) {
+        if self.delegate.is_some() {
+            unsafe {
+                let superview: id = msg_send![&*self.objc, superview];
+                if superview != nil {
+                    let _: () = msg_send![&*self.objc, removeFromSuperview];
+                }
+            }
+        }
+    }
+}

src/scrollview/traits.rs

@@ -0,0 +1,37 @@
+use crate::dragdrop::{DragInfo, DragOperation};
+use crate::scrollview::ScrollView;
+
+pub trait ScrollViewDelegate {
+    /// Called when the View is ready to work with. You're passed a `View` - this is safe to
+    /// store and use repeatedly, but it's not thread safe - any UI calls must be made from the
+    /// main thread!
+    fn did_load(&mut self, _view: ScrollView) {}
+
+    /// Called when this is about to be added to the view heirarchy.
+    fn will_appear(&self, _animated: bool) {}
+
+    /// Called after this has been added to the view heirarchy.
+    fn did_appear(&self, _animated: bool) {}
+
+    /// Called when this is about to be removed from the view heirarchy.
+    fn will_disappear(&self, _animated: bool) {}
+
+    /// Called when this has been removed from the view heirarchy.
+    fn did_disappear(&self, _animated: bool) {}
+
+    /// Invoked when the dragged image enters destination bounds or frame; returns dragging operation to perform.
+    fn dragging_entered(&self, _info: DragInfo) -> DragOperation { DragOperation::None }
+    
+    /// Invoked when the image is released, allowing the receiver to agree to or refuse drag operation.
+    fn prepare_for_drag_operation(&self, _info: DragInfo) -> bool { false }
+
+    /// Invoked after the released image has been removed from the screen, signaling the receiver to import the pasteboard data.
+    fn perform_drag_operation(&self, _info: DragInfo) -> bool { false }
+
+    /// Invoked when the dragging operation is complete, signaling the receiver to perform any necessary clean-up.
+    fn conclude_drag_operation(&self, _info: DragInfo) {}
+
+    /// Invoked when the dragged image exits the destination’s bounds rectangle (in the case of a view) or its frame 
+    /// rectangle (in the case of a window object).
+    fn dragging_exited(&self, _info: DragInfo) {}
+}

src/text/enums.rs

@@ -0,0 +1,22 @@
+
+use crate::foundation::{NSInteger, NSUInteger};
+
+pub enum TextAlign {
+    Left,
+    Right,
+    Center,
+    Justified,
+    Natural
+}
+
+impl From<TextAlign> for NSInteger {
+    fn from(alignment: TextAlign) -> Self {
+        match alignment {
+            TextAlign::Left => 0,
+            TextAlign::Center => 1,
+            TextAlign::Right => 2,
+            TextAlign::Justified => 3,
+            TextAlign::Natural => 4
+        }
+    }
+}

src/text/font.rs

@@ -0,0 +1,36 @@
+//! Implements `Font`, a wrapper around `NSFont` on macOS and `UIFont` on iOS.
+
+use core_graphics::base::CGFloat;
+
+use objc_id::ShareId;
+use objc::runtime::{Class, Object};
+use objc::{class, msg_send, sel, sel_impl};
+
+use crate::foundation::{id, nil, YES, NO, NSArray, NSString};
+
+#[derive(Debug)]
+pub struct Font {
+    pub objc: ShareId<Object>
+}
+
+impl Default for Font {
+    fn default() -> Self {
+        Font {
+            objc: unsafe {
+                let cls = class!(NSFont);
+                let default_size: id = msg_send![cls, labelFontSize];
+                msg_send![cls, labelFontOfSize:default_size]
+            }
+        }
+    }
+}
+
+impl Font {
+    pub fn system(size: CGFloat) -> Self {
+        Font {
+            objc: unsafe {
+                msg_send![class!(NSFont), systemFontOfSize:size]
+            }
+        }
+    }
+}

src/text/label/macos.rs

@@ -0,0 +1,58 @@
+//! This module does one specific thing: register a custom `NSView` class that's... brought to the
+//! modern era.
+//!
+//! I kid, I kid.
+//!
+//! It just enforces that coordinates are judged from the top-left, which is what most people look
+//! for in the modern era. It also implements a few helpers for things like setting a background
+//! color, and enforcing layer backing by default.
+
+use std::sync::Once;
+
+use objc::declare::ClassDecl;
+use objc::runtime::{Class, Object, Sel, BOOL};
+use objc::{class, sel, sel_impl};
+use objc_id::Id;
+
+use crate::foundation::{id, YES, NO, NSUInteger};
+use crate::dragdrop::DragInfo;
+use crate::text::label::{LABEL_DELEGATE_PTR, LabelDelegate};
+use crate::utils::load;
+
+/// Injects an `NSTextField` subclass. This is used for the default views that don't use delegates - we
+/// have separate classes here since we don't want to waste cycles on methods that will never be
+/// used if there's no delegates.
+pub(crate) fn register_view_class() -> *const Class {
+    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    static INIT: Once = Once::new();
+
+    INIT.call_once(|| unsafe {
+        let superclass = class!(NSTextField);
+        let mut decl = ClassDecl::new("RSTTextField", superclass).unwrap();
+        VIEW_CLASS = decl.register();
+    });
+
+    unsafe { VIEW_CLASS }
+}
+
+/// Injects an `NSTextField` subclass, with some callback and pointer ivars for what we
+/// need to do.
+pub(crate) fn register_view_class_with_delegate<T: LabelDelegate>() -> *const Class {
+    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    static INIT: Once = Once::new();
+
+    INIT.call_once(|| unsafe {
+        let superclass = class!(NSView);
+        let mut decl = ClassDecl::new("RSTTextFieldWithDelegate", superclass).unwrap();
+
+        // A pointer to the "view controller" on the Rust side. It's expected that this doesn't
+        // move.
+        decl.add_ivar::<usize>(LABEL_DELEGATE_PTR);        
+       
+        VIEW_CLASS = decl.register();
+    });
+
+    unsafe {
+        VIEW_CLASS
+    }
+}

src/text/label/mod.rs

@@ -0,0 +1,273 @@
+//! Wraps `NSTextField` and `UILabel` across platforms, explicitly as a Label.
+//! In AppKit, `NSTextField` does double duty, and for clarity we just double
+//! the implementation.
+//!
+//! Labels implement Autolayout, which enable you to specify how things should appear on the screen.
+//! 
+//! ```rust,no_run
+//! use cacao::color::rgb;
+//! use cacao::layout::{Layout, LayoutConstraint};
+//! use cacao::view::Label;
+//! use cacao::window::{Window, WindowDelegate};
+//!
+//! #[derive(Default)]
+//! struct AppWindow {
+//!     content: Label,
+//!     label: Label,
+//!     window: Window
+//! }
+//! 
+//! impl WindowDelegate for AppWindow {
+//!     fn did_load(&mut self, window: Window) {
+//!         window.set_minimum_content_size(300., 300.);
+//!         self.window = window;
+//!
+//!         self.label.set_background_color(rgb(224, 82, 99));
+//!         self.label.set_text("LOL");
+//!         self.content.add_subview(&self.red);
+//!         
+//!         self.window.set_content_view(&self.content);
+//!
+//!         LayoutConstraint::activate(&[
+//!             self.red.top.constraint_equal_to(&self.content.top).offset(16.),
+//!             self.red.leading.constraint_equal_to(&self.content.leading).offset(16.),
+//!             self.red.trailing.constraint_equal_to(&self.content.trailing).offset(-16.),
+//!             self.red.bottom.constraint_equal_to(&self.content.bottom).offset(-16.),
+//!         ]);
+//!     }
+//! }
+//! ```
+//!
+//! For more information on Autolayout, view the module or check out the examples folder.
+
+use objc_id::ShareId;
+use objc::runtime::{Class, Object};
+use objc::{msg_send, sel, sel_impl};
+
+use crate::foundation::{id, nil, YES, NO, NSArray, NSInteger, NSString};
+use crate::color::Color;
+use crate::layout::{Layout, LayoutAnchorX, LayoutAnchorY, LayoutAnchorDimension};
+use crate::text::{Font, TextAlign};
+
+#[cfg(target_os = "macos")]
+mod macos;
+
+#[cfg(target_os = "macos")]
+use macos::{register_view_class, register_view_class_with_delegate};
+
+#[cfg(target_os = "ios")]
+mod ios;
+
+#[cfg(target_os = "ios")]
+use ios::{register_view_class, register_view_class_with_delegate};
+
+//mod controller;
+//pub use controller::LabelController;
+
+mod traits;
+pub use traits::LabelDelegate;
+
+pub(crate) static LABEL_DELEGATE_PTR: &str = "rstLabelDelegatePtr";
+
+/// A helper method for instantiating view classes and applying default settings to them.
+fn allocate_view(registration_fn: fn() -> *const Class) -> id { 
+    unsafe {
+        #[cfg(target_os = "macos")]
+        let view: id = {
+            // This sucks, but for now, sure.
+            let blank = NSString::new("");
+            msg_send![registration_fn(), labelWithString:blank.into_inner()]
+        };
+
+        #[cfg(target_os = "ios")]
+        let view: id = msg_send![registration_fn(), new];
+
+        let _: () = msg_send![view, setTranslatesAutoresizingMaskIntoConstraints:NO];
+
+        #[cfg(target_os = "macos")]
+        let _: () = msg_send![view, setWantsLayer:YES];
+
+        view 
+    }
+}
+
+/// A clone-able handler to an `NSTextField/UILabel` reference in the 
+/// Objective-C runtime.
+#[derive(Debug)]
+pub struct Label<T = ()> {
+    /// A pointer to the Objective-C runtime view controller.
+    pub objc: ShareId<Object>,
+
+    /// A pointer to the delegate for this view.
+    pub delegate: Option<Box<T>>,
+
+    /// A pointer to the Objective-C runtime top layout constraint.
+    pub top: LayoutAnchorY,
+
+    /// A pointer to the Objective-C runtime leading layout constraint.
+    pub leading: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime trailing layout constraint.
+    pub trailing: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime bottom layout constraint.
+    pub bottom: LayoutAnchorY,
+
+    /// A pointer to the Objective-C runtime width layout constraint.
+    pub width: LayoutAnchorDimension,
+
+    /// A pointer to the Objective-C runtime height layout constraint.
+    pub height: LayoutAnchorDimension,
+
+    /// A pointer to the Objective-C runtime center X layout constraint.
+    pub center_x: LayoutAnchorX,
+
+    /// A pointer to the Objective-C runtime center Y layout constraint.
+    pub center_y: LayoutAnchorY
+}
+
+impl Default for Label {
+    fn default() -> Self {
+        Label::new()
+    }
+}
+
+impl Label {
+    /// Returns a default `Label`, suitable for 
+    pub fn new() -> Self {
+        let view = allocate_view(register_view_class);
+
+        Label {
+            delegate: None,
+            top: LayoutAnchorY::new(unsafe { msg_send![view, topAnchor] }),
+            leading: LayoutAnchorX::new(unsafe { msg_send![view, leadingAnchor] }),
+            trailing: LayoutAnchorX::new(unsafe { msg_send![view, trailingAnchor] }),
+            bottom: LayoutAnchorY::new(unsafe { msg_send![view, bottomAnchor] }),
+            width: LayoutAnchorDimension::new(unsafe { msg_send![view, widthAnchor] }),
+            height: LayoutAnchorDimension::new(unsafe { msg_send![view, heightAnchor] }),
+            center_x: LayoutAnchorX::new(unsafe { msg_send![view, centerXAnchor] }),
+            center_y: LayoutAnchorY::new(unsafe { msg_send![view, centerYAnchor] }),
+            objc: unsafe { ShareId::from_ptr(view) },
+        }
+    }
+}
+
+impl<T> Label<T> where T: LabelDelegate + 'static {
+    /// Initializes a new Label with a given `LabelDelegate`. This enables you to respond to events
+    /// and customize the view as a module, similar to class-based systems.
+    pub fn with(delegate: T) -> Label<T> {
+        let delegate = Box::new(delegate);
+        
+        let label = allocate_view(register_view_class_with_delegate::<T>);
+        unsafe {
+            //let view: id = msg_send![register_view_class_with_delegate::<T>(), new];
+            //let _: () = msg_send![view, setTranslatesAutoresizingMaskIntoConstraints:NO];
+            let ptr: *const T = &*delegate;
+            (&mut *label).set_ivar(LABEL_DELEGATE_PTR, ptr as usize);
+        };
+
+        let mut label = Label {
+            delegate: None,
+            top: LayoutAnchorY::new(unsafe { msg_send![label, topAnchor] }),
+            leading: LayoutAnchorX::new(unsafe { msg_send![label, leadingAnchor] }),
+            trailing: LayoutAnchorX::new(unsafe { msg_send![label, trailingAnchor] }),
+            bottom: LayoutAnchorY::new(unsafe { msg_send![label, bottomAnchor] }),
+            width: LayoutAnchorDimension::new(unsafe { msg_send![label, widthAnchor] }),
+            height: LayoutAnchorDimension::new(unsafe { msg_send![label, heightAnchor] }),
+            center_x: LayoutAnchorX::new(unsafe { msg_send![label, centerXAnchor] }),
+            center_y: LayoutAnchorY::new(unsafe { msg_send![label, centerYAnchor] }),
+            objc: unsafe { ShareId::from_ptr(label) },
+        };
+
+        //(&mut delegate).did_load(label.clone_as_handle()); 
+        label.delegate = Some(delegate);
+        label
+    }
+}
+
+impl<T> Label<T> {
+    /// An internal method that returns a clone of this object, sans references to the delegate or
+    /// callback pointer. We use this in calling `did_load()` - implementing delegates get a way to
+    /// reference, customize and use the view but without the trickery of holding pieces of the
+    /// delegate - the `Label` is the only true holder of those.
+    pub(crate) fn clone_as_handle(&self) -> Label {
+        Label {
+            delegate: None,
+            top: self.top.clone(),
+            leading: self.leading.clone(),
+            trailing: self.trailing.clone(),
+            bottom: self.bottom.clone(),
+            width: self.width.clone(),
+            height: self.height.clone(),
+            center_x: self.center_x.clone(),
+            center_y: self.center_y.clone(),
+            objc: self.objc.clone()
+        }
+    }
+
+    /// Call this to set the background color for the backing layer.
+    pub fn set_background_color(&self, color: Color) {
+        let bg = color.into_platform_specific_color();
+        
+        unsafe {
+            let cg: id = msg_send![bg, CGColor];
+            let layer: id = msg_send![&*self.objc, layer];
+            let _: () = msg_send![layer, setBackgroundColor:cg];
+        }
+    }
+
+    /// Call this to set the text for the label.
+    pub fn set_text(&self, text: &str) {
+        let s = NSString::new(text);
+
+        unsafe {
+            let _: () = msg_send![&*self.objc, setStringValue:s.into_inner()];
+        }
+    }
+
+    pub fn set_text_alignment(&self, alignment: TextAlign) {
+        unsafe {
+            let alignment: NSInteger = alignment.into();
+            let _: () = msg_send![&*self.objc, setAlignment:alignment];
+        }
+    }
+
+    pub fn set_font(&self, font: &Font) {
+        unsafe {
+            let _: () = msg_send![&*self.objc, setFont:&*font.objc];
+        }
+    }
+}
+
+impl<T> Layout for Label<T> {
+    fn get_backing_node(&self) -> ShareId<Object> {
+        self.objc.clone()
+    }
+
+    fn add_subview<V: Layout>(&self, view: &V) {
+        let backing_node = view.get_backing_node();
+
+        unsafe {
+            let _: () = msg_send![&*self.objc, addSubview:backing_node];
+        }
+    }
+}
+
+impl<T> Drop for Label<T> {
+    /// A bit of extra cleanup for delegate callback pointers. If the originating `Label` is being
+    /// dropped, we do some logic to clean it all up (e.g, we go ahead and check to see if
+    /// this has a superview (i.e, it's in the heirarchy) on the AppKit side. If it does, we go
+    /// ahead and remove it - this is intended to match the semantics of how Rust handles things).
+    ///
+    /// There are, thankfully, no delegates we need to break here.
+    fn drop(&mut self) {
+        if self.delegate.is_some() {
+            unsafe {
+                let superview: id = msg_send![&*self.objc, superview];
+                if superview != nil {
+                    let _: () = msg_send![&*self.objc, removeFromSuperview];
+                }
+            }
+        }
+    }
+}

src/text/label/traits.rs

@@ -0,0 +1,4 @@
+//! Various traits used for Labels.
+
+pub trait LabelDelegate {
+}

src/text/mod.rs

@@ -0,0 +1,11 @@
+//! The `text` module encompasses various widgets for rendering and interacting
+//! with text.
+
+pub mod label;
+pub use label::Label;
+
+pub mod enums;
+pub use enums::TextAlign;
+
+pub mod font;
+pub use font::Font;

src/utils.rs

@@ -42,6 +42,22 @@ pub fn load<'a, T>(this: &'a Object, ptr_name: &str) -> &'a T {
     }
 }
 
+pub fn async_main_thread<F>(method: F)
+where
+    F: Fn() + Send + 'static
+{
+    let queue = dispatch::Queue::main();    
+    queue.exec_async(method);
+}
+
+pub fn sync_main_thread<F>(method: F)
+where
+    F: Fn() + Send + 'static
+{
+    let queue = dispatch::Queue::main();    
+    queue.exec_sync(method);    
+}
+
 /// Upstream core graphics does not implement Encode for certain things, so we wrap them here -
 /// these are only used in reading certain types passed to us from some delegate methods.
 #[repr(C)]
@@ -51,6 +67,12 @@ pub struct CGSize {
     pub height: CGFloat,
 }
 
+impl CGSize {
+    pub fn new(width: CGFloat, height: CGFloat) -> Self {
+        CGSize { width, height }
+    }
+}
+
 unsafe impl Encode for CGSize {
     fn encode() -> Encoding {
         let encoding = format!("{{CGSize={}{}}}",

src/view/controller/mod.rs

@@ -19,7 +19,7 @@ mod ios;
 #[cfg(target_os = "ios")]
 use ios::register_view_controller_class;
 
-//#[derive(Debug)]
+#[derive(Debug)]
 pub struct ViewController<T> {
     pub objc: ShareId<Object>,
     pub view: View<T>
@@ -27,7 +27,7 @@ pub struct ViewController<T> {
 
 impl<T> ViewController<T> where T: ViewDelegate + 'static {
     pub fn new(delegate: T) -> Self {
-        let view = View::with(delegate);
+        let mut view = View::with(delegate);
 
         let objc = unsafe {
             let vc: id = msg_send![register_view_controller_class::<T>(), new];
@@ -42,10 +42,10 @@ impl<T> ViewController<T> where T: ViewDelegate + 'static {
             ShareId::from_ptr(vc)
         };
 
-        let handle = view.clone_as_handle();
-        if let Some(view_delegate) = &view.delegate {
-            view_delegate.did_load(handle);
-        }
+        //let handle = view.clone_as_handle();
+        //if let Some(view_delegate) = &mut view.delegate {
+        //    view_delegate.did_load(handle);
+        //}
 
         ViewController {
             objc: objc,

src/view/mod.rs

@@ -149,7 +149,7 @@ impl<T> View<T> where T: ViewDelegate + 'static {
     /// Initializes a new View with a given `ViewDelegate`. This enables you to respond to events
     /// and customize the view as a module, similar to class-based systems.
     pub fn with(delegate: T) -> View<T> {
-        let delegate = Box::new(delegate);
+        let mut delegate = Box::new(delegate);
         
         let view = allocate_view(register_view_class_with_delegate::<T>);
         unsafe {
@@ -172,7 +172,7 @@ impl<T> View<T> where T: ViewDelegate + 'static {
             objc: unsafe { ShareId::from_ptr(view) },
         };
 
-        &delegate.did_load(view.clone_as_handle()); 
+        (&mut delegate).did_load(view.clone_as_handle()); 
         view.delegate = Some(delegate);
         view
     }

src/view/traits.rs

@@ -4,10 +4,10 @@ use crate::dragdrop::{DragInfo, DragOperation};
 use crate::view::View;
 
 pub trait ViewDelegate {
-    /// Called when the View is ready to work with. You're passed a `ViewHandle` - this is safe to
+    /// Called when the View is ready to work with. You're passed a `View` - this is safe to
     /// store and use repeatedly, but it's not thread safe - any UI calls must be made from the
     /// main thread!
-    fn did_load(&self, _view: View) {}
+    fn did_load(&mut self, _view: View) {}
 
     /// Called when this is about to be added to the view heirarchy.
     fn will_appear(&self, _animated: bool) {}