Merge branch 'trunk' into fix-ios-simulator-boot

Cargo.toml

@@ -23,7 +23,7 @@ block = "0.1.6"
 core-foundation = "0.9"
 core-graphics = "0.22"
 dispatch = "0.2.0"
-infer = { version = "0.11", optional = true }
+infer = { version = "0.13", optional = true }
 lazy_static = "1.4.0"
 libc = "0.2"
 objc = "0.2.7"
@@ -99,3 +99,6 @@ required-features = ["appkit"]
 [[example]]
 name = "window_controller"
 required-features = ["appkit"]
+[[exmaple]]
+name = "safe_area"
+required-features = ["appkit"]

examples/browser/main.rs

@@ -91,7 +91,9 @@ impl Dispatcher for BasicApp {
 #[derive(Default)]
 pub struct WebViewInstance;
 
-impl WebViewDelegate for WebViewInstance {}
+impl WebViewDelegate for WebViewInstance {
+    const NAME: &'static str = "BrowserWebViewDelegate";
+}
 
 struct AppWindow {
     toolbar: Toolbar<BrowserToolbar>,

examples/popover.rs

@@ -0,0 +1,186 @@
+//! This example showcases how to use a `Popover`.
+//! This requires multiple types:
+//! - A Window with a Controller / View
+//! - A Popover
+//! - Another Controller / View
+
+use cacao::appkit::menu::{Menu, MenuItem};
+use cacao::appkit::window::{Window, WindowConfig, WindowController, WindowDelegate};
+use cacao::appkit::{App, AppDelegate};
+use cacao::button::Button;
+use cacao::geometry::{Edge, Rect};
+use cacao::layout::{Layout, LayoutConstraint};
+use cacao::notification_center::Dispatcher;
+use cacao::text::{Font, Label};
+use cacao::view::{Popover, PopoverConfig, View, ViewController, ViewDelegate};
+
+struct BasicApp {
+    window: WindowController<MyWindow>
+}
+
+impl AppDelegate for BasicApp {
+    fn did_finish_launching(&self) {
+        App::set_menu(vec![
+            Menu::new("", vec![
+                MenuItem::Services,
+                MenuItem::Separator,
+                MenuItem::Hide,
+                MenuItem::HideOthers,
+                MenuItem::ShowAll,
+                MenuItem::Separator,
+                MenuItem::Quit,
+            ]),
+            Menu::new("File", vec![MenuItem::CloseWindow]),
+            Menu::new("View", vec![MenuItem::EnterFullScreen]),
+            Menu::new("Window", vec![
+                MenuItem::Minimize,
+                MenuItem::Zoom,
+                MenuItem::Separator,
+                MenuItem::new("Bring All to Front"),
+            ]),
+        ]);
+
+        App::activate();
+
+        self.window.show();
+    }
+
+    fn should_terminate_after_last_window_closed(&self) -> bool {
+        true
+    }
+}
+
+#[derive(Default)]
+struct MyWindow {
+    controller: Option<ViewController<PopoverExampleContentView>>
+}
+
+impl WindowDelegate for MyWindow {
+    const NAME: &'static str = "MyWindow";
+
+    fn did_load(&mut self, window: Window) {
+        window.set_minimum_content_size(400., 400.);
+        window.set_title("A Basic Window!?");
+        let view = PopoverExampleContentView::new();
+        let controller = ViewController::new(view);
+        window.set_content_view_controller(&controller);
+        self.controller = Some(controller);
+    }
+
+    fn will_close(&self) {
+        println!("Closing now!");
+    }
+}
+
+impl MyWindow {
+    pub fn on_message(&self, message: Msg) {
+        if let Some(delegate) = self.controller.as_ref().map(|e| &e.view).and_then(|v| v.delegate.as_ref()) {
+            delegate.on_message(message);
+        }
+    }
+}
+
+fn main() {
+    App::new("com.test.window-delegate", BasicApp {
+        window: WindowController::with(WindowConfig::default(), MyWindow::default())
+    })
+    .run();
+}
+
+#[derive(Clone, Debug)]
+pub enum Msg {
+    Click
+}
+
+#[derive(Debug, Default)]
+struct PopoverExampleContentView {
+    view: Option<View>,
+    button: Option<Button>,
+    popover: Option<Popover<PopoverExampleContentViewController>>
+}
+
+impl PopoverExampleContentView {
+    pub fn new() -> Self {
+        Self {
+            view: None,
+            button: None,
+            popover: None
+        }
+    }
+
+    pub fn on_message(&self, message: Msg) {
+        match message {
+            Msg::Click => {
+                let Some(ref popover) = self.popover else { return };
+                let Some(ref button) = self.button else { return };
+                popover.show_popover(Rect::zero(), button, Edge::MaxY);
+            }
+        }
+    }
+}
+
+impl ViewDelegate for PopoverExampleContentView {
+    const NAME: &'static str = "PopoverExampleContentView";
+
+    fn did_load(&mut self, view: cacao::view::View) {
+        let mut button = Button::new("Show");
+        button.set_action(|| dispatch_ui(Msg::Click));
+
+        let controller = PopoverExampleContentViewController::new();
+        let config = PopoverConfig {
+            animates: false,
+            ..Default::default()
+        };
+        let popover = Popover::new(controller, config);
+        self.popover = Some(popover);
+
+        view.add_subview(&button);
+
+        LayoutConstraint::activate(&[
+            button.center_x.constraint_equal_to(&view.center_x),
+            button.center_y.constraint_equal_to(&view.center_y)
+        ]);
+
+        self.view = Some(view);
+        self.button = Some(button);
+    }
+}
+
+pub fn dispatch_ui(message: Msg) {
+    println!("Dispatching UI message: {:?}", message);
+    App::<BasicApp, Msg>::dispatch_main(message);
+}
+
+impl Dispatcher for BasicApp {
+    type Message = Msg;
+
+    // Handles a message that came over on the main (UI) thread.
+    fn on_ui_message(&self, message: Self::Message) {
+        if let Some(d) = &self.window.window.delegate {
+            d.on_message(message)
+        }
+    }
+}
+
+#[derive(Debug)]
+struct PopoverExampleContentViewController {
+    pub label: Label
+}
+
+impl PopoverExampleContentViewController {
+    fn new() -> Self {
+        let label = Label::new();
+        let font = Font::system(20.);
+        label.set_font(&font);
+        label.set_text("Hello");
+        Self { label }
+    }
+}
+
+impl ViewDelegate for PopoverExampleContentViewController {
+    const NAME: &'static str = "PopoverExampleContentViewController";
+
+    fn did_load(&mut self, view: View) {
+        view.add_subview(&self.label);
+    }
+}

examples/readme.md

@@ -40,6 +40,11 @@ This example showcases text input, and logs it to the underlying console. It's m
 
 `cargo run --example text_input`
 
+## Safe Area
+This example showcases A window containg the text "Hello, world!" while keeping everything in the safearea to keep it visible.
+
+`cargo run --example safe_area`
+
 ## Calculator
 A Rust-rendition of the macOS Calculator app.
 

examples/safe_area.rs

@@ -0,0 +1,63 @@
+//! This example showcases setting up a basic application and view with safe area constraints.
+
+use cacao::appkit::window::Window;
+use cacao::appkit::{App, AppDelegate};
+use cacao::layout::{Layout, LayoutConstraint};
+use cacao::text::{Font, Label};
+use cacao::view::{View, ViewDelegate};
+
+struct BasicApp {
+    window: Window,
+    content_view: View<ContentView>
+}
+
+impl AppDelegate for BasicApp {
+    fn did_finish_launching(&self) {
+        App::activate();
+
+        self.window.set_minimum_content_size(400., 400.);
+        self.window.set_title("Safe Area Demo");
+        self.window.set_content_view(&self.content_view);
+        self.window.show();
+    }
+
+    fn should_terminate_after_last_window_closed(&self) -> bool {
+        true
+    }
+}
+
+#[derive(Default)]
+struct ContentView {
+    content: View,
+    label: Label
+}
+
+impl ViewDelegate for ContentView {
+    const NAME: &'static str = "SafeAreaView";
+
+    fn did_load(&mut self, view: View) {
+        let font = Font::system(30.);
+        self.label.set_font(&font);
+        self.label.set_text("Hello World");
+        self.label.set_text_color(cacao::color::Color::rgb(255, 255, 255));
+
+        self.content.add_subview(&self.label);
+        view.add_subview(&self.content);
+
+        // Add layout constraints to be 100% excluding the safe area
+        // Do last because it will crash because the view needs to be inside the hierarchy
+        cacao::layout::LayoutConstraint::activate(&[
+            self.content.top.constraint_equal_to(&view.safe_layout_guide.top),
+            self.content.leading.constraint_equal_to(&view.safe_layout_guide.leading),
+            self.content.trailing.constraint_equal_to(&view.safe_layout_guide.trailing),
+            self.content.bottom.constraint_equal_to(&view.safe_layout_guide.bottom),
+        ])
+    }
+}
+
+fn main() {
+    App::new("com.test.window", BasicApp {
+        window: Window::default(),
+        content_view: View::with(ContentView::default())
+    }).run();
+}

examples/webview_custom_protocol.rs

@@ -23,6 +23,8 @@ impl AppDelegate for BasicApp {
 pub struct WebViewInstance;
 
 impl WebViewDelegate for WebViewInstance {
+    const NAME: &'static str = "CustomWebViewDelegate";
+
     fn on_custom_protocol_request(&self, path: &str) -> Option<Vec<u8>> {
         let requested_asset_path = path.replace("cacao://", "");
 

src/appkit/app/class.rs

@@ -2,22 +2,11 @@
 //! creates a custom `NSApplication` subclass that currently does nothing; this is meant as a hook
 //! for potential future use.
 
-use std::sync::Once;
-
-use objc::class;
-use objc::declare::ClassDecl;
 use objc::runtime::Class;
 
+use crate::foundation::load_or_register_class;
+
 /// Used for injecting a custom NSApplication. Currently does nothing.
 pub(crate) fn register_app_class() -> *const Class {
-    static mut APP_CLASS: *const Class = 0 as *const Class;
+    load_or_register_class("NSApplication", "RSTApplication", |decl| unsafe {})
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(NSApplication);
-        let decl = ClassDecl::new("RSTApplication", superclass).unwrap();
-        APP_CLASS = decl.register();
-    });
-
-    unsafe { APP_CLASS }
 }

src/appkit/app/delegate.rs

@@ -3,24 +3,19 @@
 //! for potential future use.
 
 use std::ffi::c_void;
-use std::sync::Once;
 
 use block::Block;
-
-use objc::declare::ClassDecl;
 use objc::runtime::{Class, Object, Sel};
-use objc::{class, msg_send, sel, sel_impl};
+use objc::{msg_send, sel, sel_impl};
-
 use url::Url;
 
 use crate::appkit::app::{AppDelegate, APP_PTR};
 use crate::appkit::printing::PrintSettings;
-use crate::error::Error;
-use crate::foundation::{id, nil, to_bool, NSArray, NSString, NSUInteger, BOOL, NO, YES};
-use crate::user_activity::UserActivity;
-
 #[cfg(feature = "cloudkit")]
 use crate::cloudkit::share::CKShareMetaData;
+use crate::error::Error;
+use crate::foundation::{id, load_or_register_class, nil, to_bool, NSArray, NSString, NSUInteger, BOOL, NO, YES};
+use crate::user_activity::UserActivity;
 
 /// A handy method for grabbing our `AppDelegate` from the pointer. This is different from our
 /// standard `utils` version as this doesn't require `RefCell` backing.
@@ -295,13 +290,7 @@ extern "C" fn delegate_handles_key<T: AppDelegate>(this: &Object, _: Sel, _: id,
 /// Registers an `NSObject` application delegate, and configures it for the various callbacks and
 /// pointers we need to have.
 pub(crate) fn register_app_delegate_class<T: AppDelegate + AppDelegate>() -> *const Class {
-    static mut DELEGATE_CLASS: *const Class = 0 as *const Class;
+    load_or_register_class("NSObject", "RSTAppDelegate", |decl| unsafe {
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(NSObject);
-        let mut decl = ClassDecl::new("RSTAppDelegate", superclass).unwrap();
-
         decl.add_ivar::<usize>(APP_PTR);
 
         // Launching Applications
@@ -461,9 +450,5 @@ pub(crate) fn register_app_delegate_class<T: AppDelegate + AppDelegate>() -> *co
             sel!(application:delegateHandlesKey:),
             delegate_handles_key::<T> as extern "C" fn(&Object, _, _, id) -> BOOL
         );
-
+    })
-        DELEGATE_CLASS = decl.register();
-    });
-
-    unsafe { DELEGATE_CLASS }
 }

src/appkit/app/mod.rs

@@ -63,13 +63,15 @@ pub use enums::*;
 mod traits;
 pub use traits::AppDelegate;
 
+use super::window::Window;
+
 pub(crate) static APP_PTR: &str = "rstAppPtr";
 
 /// A handler to make some boilerplate less annoying.
 #[inline]
-fn shared_application<F: Fn(id)>(handler: F) {
+fn shared_application<T, F: Fn(id) -> T>(handler: F) -> T {
     let app: id = unsafe { msg_send![register_app_class(), sharedApplication] };
-    handler(app);
+    handler(app)
 }
 
 /// A wrapper for `NSApplication` in AppKit/Cocoa, and `UIApplication` in UIKit/Cocoa Touch.
@@ -298,6 +300,13 @@ impl App {
         });
     }
 
+    pub fn main_window() -> Window {
+        shared_application(|app| unsafe {
+            let window: id = msg_send![app, mainWindow];
+            Window::existing(window)
+        })
+    }
+
     /// 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/appkit/menu/item.rs

@@ -3,16 +3,13 @@
 //! now.
 
 use std::fmt;
-use std::sync::Once;
 
-use block::ConcreteBlock;
-use objc::declare::ClassDecl;
 use objc::runtime::{Class, Object, Sel};
 use objc::{class, msg_send, sel, sel_impl};
 use objc_id::Id;
 
 use crate::events::EventModifierFlag;
-use crate::foundation::{id, nil, NSString, NSUInteger};
+use crate::foundation::{id, load_or_register_class, NSString, NSUInteger};
 
 static BLOCK_PTR: &'static str = "cacaoMenuItemBlockPtr";
 
@@ -314,19 +311,10 @@ extern "C" fn fire_block_action(this: &Object, _: Sel, _item: id) {
 /// In general, we do not want to do more than we need to here - menus are one of the last areas
 /// where Carbon still lurks, and subclassing things can get weird.
 pub(crate) fn register_menu_item_class() -> *const Class {
-    static mut APP_CLASS: *const Class = 0 as *const Class;
+    load_or_register_class("NSMenuItem", "CacaoMenuItem", |decl| unsafe {
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(NSMenuItem);
-        let mut decl = ClassDecl::new("CacaoMenuItem", superclass).unwrap();
         decl.add_ivar::<usize>(BLOCK_PTR);
 
         decl.add_method(sel!(dealloc), dealloc_cacao_menuitem as extern "C" fn(&Object, _));
         decl.add_method(sel!(fireBlockAction:), fire_block_action as extern "C" fn(&Object, _, id));
-
+    })
-        APP_CLASS = decl.register();
-    });
-
-    unsafe { APP_CLASS }
 }

src/appkit/window/controller/class.rs

@@ -1,26 +1,15 @@
 //! Everything useful for the `WindowController`. Handles injecting an `NSWindowController` subclass
 //! into the Objective C runtime, which loops back to give us lifecycle methods.
 
-use std::sync::Once;
-
-use objc::class;
-use objc::declare::ClassDecl;
 use objc::runtime::Class;
 
 use crate::appkit::window::{WindowDelegate, WINDOW_DELEGATE_PTR};
+use crate::foundation::load_or_register_class;
 
 /// Injects an `NSWindowController` subclass, with some callback and pointer ivars for what we
 /// need to do.
 pub(crate) fn register_window_controller_class<T: WindowDelegate>() -> *const Class {
-    static mut DELEGATE_CLASS: *const Class = 0 as *const Class;
+    load_or_register_class("NSWindowController", "RSTWindowController", |decl| unsafe {
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(NSWindowController);
-        let mut decl = ClassDecl::new("RSTWindowController", superclass).unwrap();
         decl.add_ivar::<usize>(WINDOW_DELEGATE_PTR);
-        DELEGATE_CLASS = decl.register();
+    })
-    });
-
-    unsafe { DELEGATE_CLASS }
 }

src/appkit/window/mod.rs

@@ -23,6 +23,7 @@ use crate::foundation::{id, nil, to_bool, NSInteger, NSString, NSUInteger, NO, Y
 use crate::layout::Layout;
 use crate::objc_access::ObjcAccess;
 use crate::utils::{os, Controller};
+use crate::view::View;
 
 mod class;
 use class::register_window_class_with_delegate;
@@ -112,6 +113,13 @@ impl Window {
             delegate: None
         }
     }
+
+    pub(crate) unsafe fn existing(window: *mut Object) -> Window {
+        Window {
+            objc: ShareId::from_ptr(window),
+            delegate: None
+        }
+    }
 }
 
 impl<T> Window<T>
@@ -197,6 +205,19 @@ impl<T> Window<T> {
         }
     }
 
+    /// Sets the subtitle (smaller text bellow the title on unified and expanded title bars) on the 
+    /// underlying window. When this property is an empty string, the system removes the subtitle
+    /// from the window layout. Allocates and passes an `NSString` over to the Objective C runtime.
+    /// Does nothing when less than version 11.
+    pub fn set_subtittle(&self, subtitle: &str) {
+        if !os::is_minimum_version(11) { return; }
+
+        unsafe {
+            let subtitle = NSString::new(subtitle);
+            let _: () = msg_send![&*self.objc, setSubtitle: subtitle];
+        }
+    }
+
     /// Sets the title visibility for the underlying window.
     pub fn set_title_visibility(&self, visibility: TitleVisibility) {
         unsafe {
@@ -291,6 +312,11 @@ impl<T> Window<T> {
         }
     }
 
+    /// Return the objc ContentView from the window
+    pub(crate) unsafe fn content_view(&self) -> id {
+        let id: *mut Object = msg_send![&*self.objc, contentView];
+        id
+    }
     /// Given a view, sets it as the content view for this window.
     pub fn set_content_view<L: Layout + 'static>(&self, view: &L) {
         view.with_backing_obj_mut(|backing_node| unsafe {

src/button/mod.rs

@@ -21,36 +21,28 @@
 //! my_view.add_subview(&button);
 //! ```
 
-use std::fmt;
+use objc::runtime::{Class, Object};
-use std::sync::Once;
+use objc::{msg_send, sel, sel_impl};
-
-use std::cell::RefCell;
-use std::rc::Rc;
-
-use objc::declare::ClassDecl;
-use objc::runtime::{Class, Object, Sel};
-use objc::{class, msg_send, sel, sel_impl};
 use objc_id::ShareId;
 
+pub use enums::*;
+
+#[cfg(feature = "appkit")]
+use crate::appkit::FocusRingType;
 use crate::color::Color;
 use crate::control::Control;
-use crate::foundation::{id, nil, NSString, NSUInteger, BOOL, NO, YES};
+use crate::foundation::{id, load_or_register_class, nil, NSString, NSUInteger, NO, YES};
 use crate::image::Image;
 use crate::invoker::TargetActionHandler;
 use crate::keys::Key;
 use crate::layout::Layout;
-use crate::objc_access::ObjcAccess;
-use crate::text::{AttributedString, Font};
-use crate::utils::{load, properties::ObjcProperty};
-
 #[cfg(feature = "autolayout")]
 use crate::layout::{LayoutAnchorDimension, LayoutAnchorX, LayoutAnchorY};
-
+use crate::objc_access::ObjcAccess;
-#[cfg(feature = "appkit")]
+use crate::text::{AttributedString, Font};
-use crate::appkit::FocusRingType;
+use crate::utils::properties::ObjcProperty;
 
 mod enums;
-pub use enums::*;
 
 /// Wraps `NSButton` on appkit, and `UIButton` on iOS and tvOS.
 ///
@@ -313,6 +305,7 @@ impl ObjcAccess for Button {
 }
 
 impl Layout for Button {}
+
 impl Control for Button {}
 
 impl ObjcAccess for &Button {
@@ -326,6 +319,7 @@ impl ObjcAccess for &Button {
 }
 
 impl Layout for &Button {}
+
 impl Control for &Button {}
 
 impl Drop for Button {
@@ -343,14 +337,5 @@ impl Drop for Button {
 /// 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;
+    load_or_register_class("NSButton", "RSTButton", |decl| unsafe {})
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(NSButton);
-        let decl = ClassDecl::new("RSTButton", superclass).unwrap();
-        VIEW_CLASS = decl.register();
-    });
-
-    unsafe { VIEW_CLASS }
 }

src/color/appkit_dynamic_color.rs

@@ -10,16 +10,11 @@
 //! that enables this functionality, we want to be able to provide this with some level of
 //! backwards compatibility for Mojave, as that's still a supported OS.
 
-use std::os::raw::c_void;
-use std::sync::Once;
-
 use core_graphics::base::CGFloat;
-
+use objc::runtime::{Class, Object, Sel};
-use objc::declare::ClassDecl;
-use objc::runtime::{Class, Object, Sel, BOOL};
 use objc::{class, msg_send, sel, sel_impl};
 
-use crate::foundation::{id, nil, NSArray, NSInteger, NSString, NSUInteger, NO, YES};
+use crate::foundation::{id, load_or_register_class, nil, NSArray, NSInteger};
 use crate::utils::os;
 
 pub(crate) const AQUA_LIGHT_COLOR_NORMAL_CONTRAST: &'static str = "AQUA_LIGHT_COLOR_NORMAL_CONTRAST";
@@ -259,13 +254,7 @@ extern "C" fn color_with_system_effect(this: &Object, _: Sel, effect: NSInteger)
 }
 
 pub(crate) fn register_class() -> *const Class {
-    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    load_or_register_class("NSColor", "CacaoDynamicColor", |decl| unsafe {
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(NSColor);
-        let mut decl = ClassDecl::new("CacaoDynamicColor", superclass).unwrap();
-
         // These methods all need to be forwarded, so let's hook them up.
         decl.add_method(sel!(colorSpace), color_space as extern "C" fn(&Object, _) -> id);
         decl.add_method(
@@ -359,9 +348,5 @@ pub(crate) fn register_class() -> *const Class {
         decl.add_ivar::<id>(AQUA_LIGHT_COLOR_HIGH_CONTRAST);
         decl.add_ivar::<id>(AQUA_DARK_COLOR_NORMAL_CONTRAST);
         decl.add_ivar::<id>(AQUA_DARK_COLOR_HIGH_CONTRAST);
-
+    })
-        VIEW_CLASS = decl.register();
-    });
-
-    unsafe { VIEW_CLASS }
 }

src/foundation/class.rs

@@ -1,9 +1,13 @@
+use std::cell::Cell;
+use std::collections::hash_map::DefaultHasher;
 use std::collections::HashMap;
 use std::ffi::CString;
+use std::hash::{Hash, Hasher};
 use std::sync::{Arc, RwLock};
+use std::thread;
+use std::time::Instant;
 
 use lazy_static::lazy_static;
-
 use objc::declare::ClassDecl;
 use objc::runtime::{objc_getClass, Class};
 
@@ -11,98 +15,98 @@ lazy_static! {
     static ref CLASSES: ClassMap = ClassMap::new();
 }
 
+thread_local! {
+    /// A very simple RNG seed that we use in constructing unique subclass names.
+    ///
+    /// Why are we doing this? Mainly because I just don't want to bring in another
+    /// crate for something that can be done like this; we don't need cryptographically
+    /// secure generation or anything fancy, as we're just after a unique dangling bit
+    /// for class names.
+    static RNG_SEED: Cell<u64> = Cell::new({
+        let mut hasher = DefaultHasher::new();
+        Instant::now().hash(&mut hasher);
+        thread::current().id().hash(&mut hasher);
+        let hash = hasher.finish();
+        (hash << 1) | 1
+    });
+}
+
+/// Represents an entry in a `ClassMap`. We store an optional superclass_name for debugging
+/// purposes; it's an `Option` to make the logic of loading a class type where we don't need to
+/// care about the superclass type simpler.
+#[derive(Debug)]
+struct ClassEntry {
+    pub superclass_name: Option<&'static str>,
+    pub ptr: usize
+}
+
+/// Represents a key in a `ClassMap`.
+type ClassKey = (&'static str, Option<&'static str>);
+
 /// A ClassMap is a general cache for our Objective-C class lookup and registration. Rather than
 /// constantly calling into the runtime, we store pointers to Class types here after first lookup
-/// and/or creation. The general store format is (roughly speaking) as follows:
+/// and/or creation.
-///
-/// ```ignore
-/// {
-///     "subclass_type": {
-///         "superclass_type": *const Class as usize
-///     }
-/// }
-/// ```
-///
-/// The reasoning behind the double map is that it allows for lookup without allocating a `String`
-/// on each hit; allocations are only required when creating a Class to inject, purely for naming
-/// and debugging reasons.
 ///
 /// There may be a way to do this without using HashMaps and avoiding the heap, but working and
 /// usable beats ideal for now. Open to suggestions.
 #[derive(Debug)]
-pub(crate) struct ClassMap(RwLock<HashMap<&'static str, HashMap<&'static str, usize>>>);
+pub(crate) struct ClassMap(RwLock<HashMap<ClassKey, ClassEntry>>);
 
 impl ClassMap {
     /// Returns a new ClassMap.
     pub fn new() -> Self {
-        ClassMap(RwLock::new({
+        ClassMap(RwLock::new(HashMap::new()))
-            let mut map = HashMap::new();
-
-            // Top-level classes, like `NSView`, we cache here. The reasoning is that if a subclass
-            // is being created, we can avoid querying the runtime for the superclass - i.e, many
-            // subclasses will have `NSView` as their superclass.
-            map.insert("_supers", HashMap::new());
-
-            map
-        }))
     }
 
-    /// Attempts to load a previously registered subclass.
+    /// Attempts to load a previously registered class.
-    pub fn load_subclass(&self, subclass_name: &'static str, superclass_name: &'static str) -> Option<*const Class> {
+    ///
-        let reader = self.0.read().unwrap();
+    /// This checks our internal map first, and then calls out to the Objective-C runtime to ensure
-
+    /// we're not missing anything.
-        if let Some(inner) = (*reader).get(subclass_name) {
+    pub fn load(&self, class_name: &'static str, superclass_name: Option<&'static str>) -> Option<*const Class> {
-            if let Some(class) = inner.get(superclass_name) {
-                return Some(*class as *const Class);
-            }
-        }
-
-        None
-    }
-
-    /// Store a newly created subclass type.
-    pub fn store_subclass(&self, subclass_name: &'static str, superclass_name: &'static str, class: *const Class) {
-        let mut writer = self.0.write().unwrap();
-
-        if let Some(map) = (*writer).get_mut(subclass_name) {
-            map.insert(superclass_name, class as usize);
-        } else {
-            let mut map = HashMap::new();
-            map.insert(superclass_name, class as usize);
-            (*writer).insert(subclass_name, map);
-        }
-    }
-
-    /// Attempts to load a Superclass. This first checks for the cached pointer; if not present, it
-    /// will load the superclass from the Objective-C runtime and cache it for future lookup. This
-    /// assumes that the class is one that should *already* and *always* exist in the runtime, and
-    /// by design will panic if it can't load the correct superclass, as that would lead to very
-    /// invalid behavior.
-    pub fn load_superclass(&self, name: &'static str) -> Option<*const Class> {
         {
             let reader = self.0.read().unwrap();
-            if let Some(superclass) = (*reader)["_supers"].get(name) {
+            if let Some(entry) = (*reader).get(&(class_name, superclass_name)) {
-                return Some(*superclass as *const Class);
+                let ptr = &entry.ptr;
+                return Some(*ptr as *const Class);
             }
         }
 
-        let objc_superclass_name = CString::new(name).unwrap();
+        // If we don't have an entry for the class_name in our internal map, we should still check
-        let superclass = unsafe { objc_getClass(objc_superclass_name.as_ptr() as *const _) };
+        // if we can load it from the Objective-C runtime directly. The reason we need to do this
+        // is that there's a use-case where someone might have multiple bundles attempting to
+        // use or register the same subclass; Rust doesn't see the same pointers unlike the Objective-C
+        // runtime, and we can wind up in a situation where we're attempting to register a Class
+        // that already exists but we can't see.
+        let objc_class_name = CString::new(class_name).unwrap();
+        let class = unsafe { objc_getClass(objc_class_name.as_ptr() as *const _) };
 
-        // This should not happen, for our use-cases, but it's conceivable that this could actually
+        // This should not happen for our use-cases, but it's conceivable that this could actually
         // be expected, so just return None and let the caller panic if so desired.
-        if superclass.is_null() {
+        if class.is_null() {
             return None;
         }
 
+        // If we got here, then this class exists in the Objective-C runtime but is not known to
+        // us. For consistency's sake, we'll add this to our store and return that.
         {
             let mut writer = self.0.write().unwrap();
-            if let Some(supers) = (*writer).get_mut("_supers") {
+            writer.insert((class_name, superclass_name), ClassEntry {
-                supers.insert(name, superclass as usize);
+                superclass_name,
-            }
+                ptr: class as usize
+            });
         }
 
-        Some(superclass)
+        Some(class)
+    }
+
+    /// Store a newly created subclass type.
+    pub fn store(&self, class_name: &'static str, superclass_name: Option<&'static str>, class: *const Class) {
+        let mut writer = self.0.write().unwrap();
+
+        writer.insert((class_name, superclass_name), ClassEntry {
+            superclass_name,
+            ptr: class as usize
+        });
     }
 }
 
@@ -124,19 +128,37 @@ pub fn load_or_register_class<F>(superclass_name: &'static str, subclass_name: &
 where
     F: Fn(&mut ClassDecl) + 'static
 {
-    if let Some(subclass) = CLASSES.load_subclass(subclass_name, superclass_name) {
+    if let Some(subclass) = CLASSES.load(subclass_name, Some(superclass_name)) {
         return subclass;
     }
 
-    if let Some(superclass) = CLASSES.load_superclass(superclass_name) {
+    // If we can't find the class anywhere, then we'll attempt to load the superclass and register
-        let objc_subclass_name = format!("{}_{}", subclass_name, superclass_name);
+    // our new class type.
+    if let Some(superclass) = CLASSES.load(superclass_name, None) {
+        // When we're generating a new Subclass name, we need to append a random-ish component
+        // due to some oddities that can come up in certain scenarios (e.g, various bundler
+        // situations appear to have odd rules about subclass name usage/registration, this simply
+        // guarantees that we almost always have a unique name to register with the ObjC runtime).
+        //
+        // For more context, see: https://github.com/ryanmcgrath/cacao/issues/63
+        let objc_subclass_name = format!(
+            "{}_{}_{}",
+            subclass_name,
+            superclass_name,
+            RNG_SEED.with(|rng| {
+                rng.set(rng.get().wrapping_add(0xa0761d6478bd642f));
+                let s = rng.get();
+                let t = u128::from(s) * (u128::from(s ^ 0xe7037ed1a0b428db));
+                ((t >> 64) as u64) ^ (t as u64)
+            })
+        );
 
         match ClassDecl::new(&objc_subclass_name, unsafe { &*superclass }) {
             Some(mut decl) => {
                 config(&mut decl);
 
                 let class = decl.register();
-                CLASSES.store_subclass(subclass_name, superclass_name, class);
+                CLASSES.store(subclass_name, Some(superclass_name), class);
                 return class;
             },
 

src/geometry.rs

@@ -41,6 +41,14 @@ impl Rect {
     }
 }
 
+#[derive(Debug, Eq, PartialEq, Copy, Clone)]
+#[repr(u32)]
+pub enum Edge {
+    MinX = 0,
+    MinY = 1,
+    MaxX = 2,
+    MaxY = 3
+}
 impl From<Rect> for CGRect {
     fn from(rect: Rect) -> CGRect {
         CGRect::new(&CGPoint::new(rect.left, rect.top), &CGSize::new(rect.width, rect.height))

src/image/appkit.rs

@@ -7,33 +7,15 @@
 //! 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::runtime::Class;
 
-use objc::declare::ClassDecl;
+use crate::foundation::load_or_register_class;
-use objc::runtime::{Class, Object, Sel, BOOL};
-use objc::{class, sel, sel_impl};
-use objc_id::Id;
-
-use crate::dragdrop::DragInfo;
-use crate::foundation::{id, NSUInteger, NO, YES};
-use crate::utils::load;
-use crate::view::{ViewDelegate, VIEW_DELEGATE_PTR};
 
 /// 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;
+    load_or_register_class("NSImageView", "RSTImageView", |decl| unsafe {
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(NSImageView);
-        let decl = ClassDecl::new("RSTImageView", superclass).unwrap();
-
         //decl.add_method(sel!(isFlipped), enforce_normalcy as extern "C" fn(&Object, _) -> BOOL);
-
+    })
-        VIEW_CLASS = decl.register();
-    });
-
-    unsafe { VIEW_CLASS }
 }

src/image/uikit.rs

@@ -1,26 +1,10 @@
-use std::sync::Once;
+use objc::runtime::Class;
 
-use objc::declare::ClassDecl;
+use crate::foundation::load_or_register_class;
-use objc::runtime::{Class, Object, Sel, BOOL};
-use objc::{class, sel, sel_impl};
-use objc_id::Id;
-
-use crate::foundation::{id, NSUInteger, NO, YES};
-use crate::utils::load;
-use crate::view::{ViewDelegate, VIEW_DELEGATE_PTR};
 
 /// 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;
+    load_or_register_class("UIImageView", "RSTImageView", |decl| unsafe {})
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(UIImageView);
-        let mut decl = ClassDecl::new("RSTImageView", superclass).expect("Failed to get RSTVIEW");
-        VIEW_CLASS = decl.register();
-    });
-
-    unsafe { VIEW_CLASS }
 }

src/input/appkit.rs

@@ -1,12 +1,7 @@
-use std::sync::Once;
-
-use objc::declare::ClassDecl;
 use objc::runtime::{Class, Object, Sel, BOOL};
-use objc::{class, msg_send, sel, sel_impl};
+use objc::{msg_send, sel, sel_impl};
-use objc_id::Id;
 
-use crate::dragdrop::DragInfo;
+use crate::foundation::{id, load_or_register_class, NSString, NO, YES};
-use crate::foundation::{id, load_or_register_class, NSString, NSUInteger, NO, YES};
 use crate::input::{TextFieldDelegate, TEXTFIELD_DELEGATE_PTR};
 use crate::utils::load;
 
@@ -52,16 +47,7 @@ extern "C" fn text_should_end_editing<T: TextFieldDelegate>(this: &mut Object, _
 /// 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;
+    load_or_register_class("NSTextField", "RSTTextInputField", |decl| unsafe {})
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(NSTextField);
-        let 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

src/invoker.rs

@@ -9,15 +9,12 @@
 //! is going away.
 
 use std::fmt;
-use std::sync::{Arc, Mutex, Once};
 
-use block::{Block, ConcreteBlock, RcBlock};
-use objc::declare::ClassDecl;
 use objc::runtime::{Class, Object, Sel};
-use objc::{class, msg_send, sel, sel_impl};
+use objc::{msg_send, sel, sel_impl};
 use objc_id::ShareId;
 
-use crate::foundation::{id, nil, NSString};
+use crate::foundation::{id, load_or_register_class};
 use crate::utils::load;
 
 pub static ACTION_CALLBACK_PTR: &str = "rstTargetActionPtr";
@@ -95,18 +92,8 @@ extern "C" fn perform<F: Fn() + 'static>(this: &mut Object, _: Sel, _sender: id)
 /// 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;
+    load_or_register_class("NSObject", "RSTTargetActionHandler", |decl| unsafe {
-    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 "C" fn(&mut Object, _, id));
-
+    })
-        VIEW_CLASS = decl.register();
-    });
-
-    unsafe { VIEW_CLASS }
 }

src/lib.rs

@@ -153,7 +153,7 @@ pub mod layout;
 pub mod listview;
 pub mod networking;
 pub mod notification_center;
-pub(crate) mod objc_access;
+pub mod objc_access;
 
 #[cfg(feature = "appkit")]
 pub mod pasteboard;

src/listview/appkit.rs

@@ -7,16 +7,13 @@
 //! 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, msg_send, sel, sel_impl};
+use objc::{msg_send, sel, sel_impl};
 use objc_id::Id;
 
-use crate::appkit::menu::{Menu, MenuItem};
+use crate::appkit::menu::Menu;
 use crate::dragdrop::DragInfo;
-use crate::foundation::{id, load_or_register_class, nil, NSArray, NSInteger, NSUInteger, NO, YES};
+use crate::foundation::{id, load_or_register_class, NSArray, NSInteger, NSUInteger, NO, YES};
 use crate::listview::{ListViewDelegate, RowEdge, LISTVIEW_DELEGATE_PTR};
 use crate::utils::load;
 
@@ -185,16 +182,7 @@ extern "C" fn dragging_exited<T: ListViewDelegate>(this: &mut Object, _: Sel, in
 /// `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;
+    load_or_register_class("NSTableView", "RSTListView", |decl| unsafe {})
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(NSTableView);
-        let 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

src/listview/row/appkit.rs

@@ -7,15 +7,12 @@
 //! 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, msg_send, sel, sel_impl};
 use objc_id::Id;
 
 use crate::dragdrop::DragInfo;
-use crate::foundation::{id, nil, NSUInteger, NO, YES};
+use crate::foundation::{id, load_or_register_class, nil, NSUInteger, NO, YES};
 use crate::listview::row::{ViewDelegate, BACKGROUND_COLOR, LISTVIEW_ROW_DELEGATE_PTR};
 use crate::utils::load;
 
@@ -107,31 +104,15 @@ extern "C" fn dealloc<T: ViewDelegate>(this: &Object, _: Sel) {
 /// 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;
+    load_or_register_class("NSView", "RSTTableViewRow", |decl| unsafe {
-    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 "C" 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;
+    load_or_register_class("NSView", "RSTableViewRowWithDelegate", |decl| unsafe {
-    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);
@@ -164,9 +145,5 @@ pub(crate) fn register_listview_row_class_with_delegate<T: ViewDelegate>() -> *c
 
         // Cleanup
         decl.add_method(sel!(dealloc), dealloc::<T> as extern "C" fn(&Object, _));
-
+    })
-        VIEW_CLASS = decl.register();
-    });
-
-    unsafe { VIEW_CLASS }
 }

src/listview/row/uikit.rs

@@ -1,45 +1,24 @@
-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::foundation::{id, NSUInteger, NO, YES};
 use crate::utils::load;
+use crate::view::{ViewDelegate, VIEW_DELEGATE_PTR};
 
 /// 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;
+    load_or_register_class("UIView", "RSTView", |decl| unsafe {})
-    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;
+    load_or_register_class("UIView", "RSTViewWithDelegate", |decl| unsafe {
-    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/scrollview/appkit.rs

@@ -7,15 +7,12 @@
 //! 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::{sel, sel_impl};
 use objc_id::Id;
 
 use crate::dragdrop::DragInfo;
-use crate::foundation::{id, NSUInteger, NO, YES};
+use crate::foundation::{id, load_or_register_class, NSUInteger, NO, YES};
 use crate::scrollview::{ScrollViewDelegate, SCROLLVIEW_DELEGATE_PTR};
 use crate::utils::load;
 
@@ -77,28 +74,13 @@ extern "C" fn dragging_exited<T: ScrollViewDelegate>(this: &mut Object, _: Sel,
 
 /// Injects an `NSScrollView` subclass.
 pub(crate) fn register_scrollview_class() -> *const Class {
-    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    load_or_register_class("NSScrollView", "RSTScrollView", |decl| unsafe {})
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(NSScrollView);
-        let 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;
+    load_or_register_class("NSScrollView", "RSTScrollViewWithDelegate", |decl| unsafe {
-    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);
@@ -126,9 +108,5 @@ pub(crate) fn register_scrollview_class_with_delegate<T: ScrollViewDelegate>() -
             sel!(draggingExited:),
             dragging_exited::<T> as extern "C" fn(&mut Object, _, _)
         );
-
+    })
-        VIEW_CLASS = decl.register();
-    });
-
-    unsafe { VIEW_CLASS }
 }

src/select/mod.rs

@@ -1,24 +1,19 @@
 //! Implements a Select-style dropdown. By default this uses NSPopupSelect on macOS.
 
-use std::sync::Once;
-
 use core_graphics::geometry::CGRect;
-
+use objc::runtime::{Class, Object};
-use objc::declare::ClassDecl;
+use objc::{msg_send, sel, sel_impl};
-use objc::runtime::{Class, Object, Sel};
-use objc::{class, msg_send, sel, sel_impl};
 use objc_id::ShareId;
 
 use crate::control::Control;
-use crate::foundation::{id, nil, NSInteger, NSString, NO, YES};
+use crate::foundation::{id, load_or_register_class, nil, NSInteger, NSString, NO, YES};
 use crate::geometry::Rect;
 use crate::invoker::TargetActionHandler;
 use crate::layout::Layout;
-use crate::objc_access::ObjcAccess;
-use crate::utils::properties::ObjcProperty;
-
 #[cfg(feature = "autolayout")]
 use crate::layout::{LayoutAnchorDimension, LayoutAnchorX, LayoutAnchorY};
+use crate::objc_access::ObjcAccess;
+use crate::utils::properties::ObjcProperty;
 
 /// Wraps `NSPopUpSelect` on AppKit. Not currently implemented for iOS.
 ///
@@ -268,14 +263,5 @@ impl Drop for Select {
 /// Registers an `NSSelect` 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;
+    load_or_register_class("NSPopUpButton", "CacaoSelect", |decl| unsafe {})
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(NSPopUpButton);
-        let decl = ClassDecl::new("CacaoSelect", superclass).unwrap();
-        VIEW_CLASS = decl.register();
-    });
-
-    unsafe { VIEW_CLASS }
 }

src/switch.rs

@@ -1,22 +1,17 @@
 //! A wrapper for NSSwitch. Currently the epitome of jank - if you're poking around here, expect
 //! that this will change at some point.
 
-use std::fmt;
+use objc::runtime::{Class, Object};
-use std::sync::Once;
+use objc::{msg_send, sel, sel_impl};
-
-use objc::declare::ClassDecl;
-use objc::runtime::{Class, Object, Sel};
-use objc::{class, msg_send, sel, sel_impl};
 use objc_id::ShareId;
 
-use crate::foundation::{id, nil, NSString, BOOL, NO, YES};
+use crate::foundation::{id, load_or_register_class, nil, NSString, NO};
 use crate::invoker::TargetActionHandler;
 use crate::layout::Layout;
-use crate::objc_access::ObjcAccess;
-use crate::utils::{load, properties::ObjcProperty};
-
 #[cfg(feature = "autolayout")]
 use crate::layout::{LayoutAnchorDimension, LayoutAnchorX, LayoutAnchorY};
+use crate::objc_access::ObjcAccess;
+use crate::utils::properties::ObjcProperty;
 
 /// A wrapper for `NSSwitch`. Holds (retains) pointers for the Objective-C runtime
 /// where our `NSSwitch` lives.
@@ -178,14 +173,5 @@ impl Drop for Switch {
 /// 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;
+    load_or_register_class("NSButton", "RSTSwitch", |decl| unsafe {})
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(NSButton);
-        let decl = ClassDecl::new("RSTSwitch", superclass).unwrap();
-        VIEW_CLASS = decl.register();
-    });
-
-    unsafe { VIEW_CLASS }
 }

src/text/font.rs

@@ -9,6 +9,7 @@ use objc::{class, msg_send, sel, sel_impl};
 use objc_id::ShareId;
 
 use crate::foundation::{id, nil, NSArray, NSString, NO, YES};
+use crate::utils::os;
 
 /// A `Font` can be constructed and applied to supported controls to control things like text
 /// appearance and size.
@@ -40,6 +41,25 @@ impl Font {
 
         Font(unsafe { ShareId::from_ptr(msg_send![class!(NSFont), boldSystemFontOfSize: size]) })
     }
+
+    /// Creates and returns a monospace system font at the specified size and weight
+    ///
+    /// # Support
+    ///
+    /// The `monospace` font feature is available from version `10.15`.
+    ///
+    /// If the current system is using an older version the `monospacedSystemFontOfSize`
+    /// option will be omitted.
+    pub fn monospace(size: f64, weight: f64) -> Self {
+        let size = size as CGFloat;
+        let weight = weight as CGFloat;
+
+        if os::is_minimum_semversion(10, 15, 0) {
+            Font(unsafe { ShareId::from_ptr(msg_send![class!(NSFont), monospacedSystemFontOfSize: size weight: weight]) })
+        } else {
+            Font(unsafe { ShareId::from_ptr(msg_send![class!(NSFont), systemFontOfSize: size weight: weight ]) })
+        }
+    }
 }
 
 impl Deref for Font {

src/text/label/appkit.rs

@@ -7,50 +7,24 @@
 //! 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::runtime::Class;
 
-use objc::declare::ClassDecl;
+use crate::foundation::load_or_register_class;
-use objc::runtime::{Class, Object, Sel, BOOL};
-use objc::{class, sel, sel_impl};
-use objc_id::Id;
-
-use crate::dragdrop::DragInfo;
-use crate::foundation::{id, NSUInteger, NO, YES};
 use crate::text::label::{LabelDelegate, LABEL_DELEGATE_PTR};
-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;
+    load_or_register_class("NSTextField", "RSTTextField", |decl| unsafe {})
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(NSTextField);
-        let 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;
+    load_or_register_class("NSView", "RSTTextFieldWithDelegate", |decl| unsafe {
-    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/uikit/app/class.rs

@@ -2,22 +2,11 @@
 //! creates a custom `UIApplication` subclass that currently does nothing; this is meant as a hook
 //! for potential future use.
 
-use std::sync::Once;
-
-use objc::class;
-use objc::declare::ClassDecl;
 use objc::runtime::Class;
 
+use crate::foundation::load_or_register_class;
+
 /// Used for injecting a custom UIApplication. Currently does nothing.
 pub(crate) fn register_app_class() -> *const Class {
-    static mut APP_CLASS: *const Class = 0 as *const Class;
+    load_or_register_class("UIApplication", "RSTApplication", |decl| unsafe {})
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(UIApplication);
-        let decl = ClassDecl::new("RSTApplication", superclass).unwrap();
-        APP_CLASS = decl.register();
-    });
-
-    unsafe { APP_CLASS }
 }

src/uikit/app/delegate.rs

@@ -2,28 +2,20 @@
 //! creates a custom `UIApplication` subclass that currently does nothing; this is meant as a hook
 //! for potential future use.
 
-//use std::ffi::c_void;
+use objc::runtime::{Class, Object, Sel};
-use std::sync::Once;
+use objc::{sel, sel_impl};
+
+//use crate::error::Error;
+use crate::foundation::{id, load_or_register_class, BOOL, YES};
+use crate::uikit::app::{AppDelegate, APP_DELEGATE};
+use crate::uikit::scene::{SceneConnectionOptions, SceneSession};
+
 //use std::unreachable;
 
 //use block::Block;
 
-use objc::declare::ClassDecl;
-use objc::runtime::{Class, Object, Sel};
-use objc::{class, msg_send, sel, sel_impl};
-
-use url::Url;
-
-//use crate::error::Error;
-use crate::foundation::{id, nil, NSArray, NSString, NSUInteger, BOOL, NO, YES};
 //use crate::user_activity::UserActivity;
 
-use crate::uikit::app::{AppDelegate, APP_DELEGATE};
-use crate::uikit::scene::{SceneConfig, SceneConnectionOptions, SceneSession};
-
-#[cfg(feature = "cloudkit")]
-use crate::cloudkit::share::CKShareMetaData;
-
 /// A handy method for grabbing our `AppDelegate` from the pointer. This is different from our
 /// standard `utils` version as this doesn't require `RefCell` backing.
 fn app<T>(this: &Object) -> &T {
@@ -49,13 +41,7 @@ extern "C" fn configuration_for_scene_session<T: AppDelegate>(this: &Object, _:
 /// Registers an `NSObject` application delegate, and configures it for the various callbacks and
 /// pointers we need to have.
 pub(crate) fn register_app_delegate_class<T: AppDelegate>() -> *const Class {
-    static mut DELEGATE_CLASS: *const Class = 0 as *const Class;
+    load_or_register_class("NSObject", "RSTAppDelegate", |decl| unsafe {
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(NSObject);
-        let mut decl = ClassDecl::new("RSTAppDelegate", superclass).unwrap();
-
         // Launching Applications
         decl.add_method(
             sel!(application:didFinishLaunchingWithOptions:),
@@ -71,9 +57,5 @@ pub(crate) fn register_app_delegate_class<T: AppDelegate>() -> *const Class {
             sel!(application:didDiscardSceneSessions:),
             did_discard_scene_sessions::<T> as extern "C" fn(&Object, _, _, id)
         );*/
-
+    })
-        DELEGATE_CLASS = decl.register();
-    });
-
-    unsafe { DELEGATE_CLASS }
 }

src/uikit/scene/delegate.rs

@@ -1,25 +1,10 @@
-use std::ffi::c_void;
+use objc::runtime::{Class, Object, Protocol, Sel};
-use std::sync::Once;
-use std::unreachable;
-
-use block::Block;
-
-use objc::declare::ClassDecl;
-use objc::runtime::{Class, Object, Sel};
 use objc::{class, msg_send, sel, sel_impl};
 
-use url::Url;
+use crate::foundation::{id, load_or_register_class};
-
-use crate::error::Error;
-use crate::foundation::{id, nil, NSArray, NSString, NSUInteger, BOOL, NO, YES};
-use crate::user_activity::UserActivity;
-use crate::utils::load;
-
 use crate::uikit::app::SCENE_DELEGATE_VENDOR;
-use crate::uikit::scene::{Scene, SceneConfig, SceneConnectionOptions, SceneSession, WindowSceneDelegate};
+use crate::uikit::scene::{Scene, SceneConnectionOptions, SceneSession, WindowSceneDelegate};
-
+use crate::utils::load;
-#[cfg(feature = "cloudkit")]
-use crate::cloudkit::share::CKShareMetaData;
 
 pub(crate) static WINDOW_SCENE_PTR: &str = "rstWindowSceneDelegatePtr";
 
@@ -60,14 +45,7 @@ extern "C" fn scene_will_connect_to_session_with_options<T: WindowSceneDelegate>
 /// Registers an `NSObject` application delegate, and configures it for the various callbacks and
 /// pointers we need to have.
 pub(crate) fn register_window_scene_delegate_class<T: WindowSceneDelegate, F: Fn() -> Box<T>>() -> *const Class {
-    static mut DELEGATE_CLASS: *const Class = 0 as *const Class;
+    load_or_register_class("UIResponder", "RSTWindowSceneDelegate", |decl| unsafe {
-    static INIT: Once = Once::new();
-
-    use objc::runtime::{class_addProtocol, Protocol};
-    INIT.call_once(|| unsafe {
-        let superclass = class!(UIResponder);
-        let mut decl = ClassDecl::new("RSTWindowSceneDelegate", superclass).unwrap();
-
         let p = Protocol::get("UIWindowSceneDelegate").unwrap();
 
         // A spot to hold a pointer to
@@ -82,10 +60,5 @@ pub(crate) fn register_window_scene_delegate_class<T: WindowSceneDelegate, F: Fn
             sel!(scene:willConnectToSession:options:),
             scene_will_connect_to_session_with_options::<T> as extern "C" fn(&Object, _, _, _, _)
         );
-
+    })
-        // Launching Applications
-        DELEGATE_CLASS = decl.register();
-    });
-
-    unsafe { DELEGATE_CLASS }
 }

src/view/appkit.rs

@@ -7,8 +7,6 @@
 //! 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, msg_send, sel, sel_impl};
@@ -92,23 +90,13 @@ extern "C" fn update_layer(this: &Object, _: Sel) {
 /// 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;
+    load_or_register_class("NSView", "RSTView", |decl| unsafe {
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(NSView);
-        let mut decl = ClassDecl::new("RSTView", superclass).unwrap();
-
         decl.add_method(sel!(isFlipped), enforce_normalcy as extern "C" fn(&Object, _) -> BOOL);
         decl.add_method(sel!(updateLayer), update_layer as extern "C" fn(&Object, _));
         decl.add_method(sel!(wantsUpdateLayer), enforce_normalcy as extern "C" fn(&Object, _) -> BOOL);
 
         decl.add_ivar::<id>(BACKGROUND_COLOR);
-
+    })
-        VIEW_CLASS = decl.register();
-    });
-
-    unsafe { VIEW_CLASS }
 }
 
 /// Injects an `NSView` subclass, with some callback and pointer ivars for what we

src/view/mod.rs

@@ -77,6 +77,8 @@ mod splitviewcontroller;
 #[cfg(feature = "appkit")]
 pub use splitviewcontroller::SplitViewController;
 
+mod popover;
+pub use popover::*;
 mod traits;
 pub use traits::ViewDelegate;
 

src/view/popover/mod.rs

@@ -0,0 +1,95 @@
+use core_graphics::geometry::CGRect;
+use objc::runtime::Object;
+use objc::{class, msg_send, sel, sel_impl};
+use objc_id::ShareId;
+
+use crate::appkit::toolbar::ToolbarItem;
+use crate::appkit::window::Window;
+use crate::appkit::App;
+use crate::foundation::{id, nil, NSString};
+use crate::geometry::{Edge, Rect};
+use crate::layout::Layout;
+use crate::utils::{os, CGSize, Controller};
+use crate::view::{View, ViewController, ViewDelegate};
+
+#[derive(Debug, Eq, PartialEq)]
+#[repr(i64)]
+pub enum PopoverBehaviour {
+    /// Your application assumes responsibility for closing the popover.
+    ApplicationDefined = 0,
+    /// The system will close the popover when the user interacts with a user interface element outside the popover.
+    Transient = 1,
+    /// The system will close the popover when the user interacts with user interface elements in the window containing the popover's positioning view.
+    Semitransient = 2
+}
+
+#[derive(Debug)]
+pub struct PopoverConfig {
+    pub content_size: CGSize,
+    pub animates: bool,
+    pub behaviour: PopoverBehaviour
+}
+
+impl Default for PopoverConfig {
+    fn default() -> Self {
+        Self {
+            content_size: CGSize {
+                width: 320.0,
+                height: 320.0
+            },
+            animates: true,
+            behaviour: PopoverBehaviour::Transient
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct Popover<Content> {
+    /// A reference to the underlying Objective-C NSPopover
+    pub objc: ShareId<Object>,
+
+    /// The wrapped ViewController.
+    pub view_controller: ViewController<Content>
+}
+
+impl<Content> Popover<Content>
+where
+    Content: ViewDelegate + 'static
+{
+    pub fn new(content: Content, config: PopoverConfig) -> Self {
+        let view_controller = ViewController::new(content);
+        let objc = unsafe {
+            let pop: id = msg_send![class!(NSPopover), new];
+            let _: () = msg_send![pop, setContentSize: config.content_size];
+            let _: () = msg_send![pop, setBehavior: config.behaviour as i64];
+            let _: () = msg_send![pop, setAnimates: config.animates];
+            let _: () = msg_send![pop, setContentViewController: &*view_controller.objc];
+
+            ShareId::from_ptr(pop)
+        };
+
+        Popover { objc, view_controller }
+    }
+}
+
+impl<Content> Popover<Content> {
+    /// Show a popover relative to a view
+    pub fn show_popover<V: Layout>(&self, relative_to: Rect, view: &V, edge: Edge) {
+        let rect: CGRect = relative_to.into();
+        unsafe {
+            view.with_backing_obj_mut(|obj| {
+                let _: () = msg_send![&*self.objc, showRelativeToRect:rect ofView: &*obj preferredEdge: edge as u32];
+            });
+        }
+    }
+
+    /// Show the popover relative to the content view of the main window
+    pub fn show_popover_main(&self, rect: Rect, edge: Edge) {
+        let window = App::main_window();
+        unsafe {
+            let content_view = window.content_view();
+            let rect: CGRect = rect.into();
+            let _: () = msg_send![&*self.objc, showRelativeToRect:rect ofView: content_view preferredEdge: edge as u32];
+        }
+    }
+}

src/view/splitviewcontroller/ios.rs

@@ -1,18 +1,15 @@
-use std::sync::Once;
-use std::unreachable;
-
 use objc::declare::ClassDecl;
 use objc::runtime::{Class, Object, Sel};
 use objc::{class, msg_send, sel, sel_impl};
 
-use crate::foundation::{BOOL};
+use crate::foundation::BOOL;
-use crate::view::{VIEW_DELEGATE_PTR, ViewDelegate};
+use crate::utils::{as_bool, load};
-use crate::utils::{load, as_bool};
+use crate::view::{ViewDelegate, VIEW_DELEGATE_PTR};
 
 /// Called when the view controller receives a `viewWillAppear:` message.
 extern "C" fn will_appear<T: ViewDelegate>(this: &mut Object, _: Sel, animated: BOOL) {
     unsafe {
-        let _: () = msg_send![super(this, class!(UIViewController)), viewWillAppear:animated];
+        let _: () = msg_send![super(this, class!(UIViewController)), viewWillAppear: animated];
     }
 
     let controller = load::<T>(this, VIEW_DELEGATE_PTR);
@@ -22,7 +19,7 @@ extern "C" fn will_appear<T: ViewDelegate>(this: &mut Object, _: Sel, animated:
 /// Called when the view controller receives a `viewDidAppear:` message.
 extern "C" fn did_appear<T: ViewDelegate>(this: &mut Object, _: Sel, animated: BOOL) {
     unsafe {
-        let _: () = msg_send![super(this, class!(UIViewController)), viewDidAppear:animated];
+        let _: () = msg_send![super(this, class!(UIViewController)), viewDidAppear: animated];
     }
 
     let controller = load::<T>(this, VIEW_DELEGATE_PTR);
@@ -32,7 +29,7 @@ extern "C" fn did_appear<T: ViewDelegate>(this: &mut Object, _: Sel, animated: B
 /// Called when the view controller receives a `viewWillDisappear:` message.
 extern "C" fn will_disappear<T: ViewDelegate>(this: &mut Object, _: Sel, animated: BOOL) {
     unsafe {
-        let _: () = msg_send![super(this, class!(UIViewController)), viewWillDisappear:animated];
+        let _: () = msg_send![super(this, class!(UIViewController)), viewWillDisappear: animated];
     }
 
     let controller = load::<T>(this, VIEW_DELEGATE_PTR);
@@ -42,7 +39,7 @@ extern "C" fn will_disappear<T: ViewDelegate>(this: &mut Object, _: Sel, animate
 /// Called when the view controller receives a `viewDidDisappear:` message.
 extern "C" fn did_disappear<T: ViewDelegate>(this: &mut Object, _: Sel, animated: BOOL) {
     unsafe {
-        let _: () = msg_send![super(this, class!(UIViewController)), viewDidDisappear:animated];
+        let _: () = msg_send![super(this, class!(UIViewController)), viewDidDisappear: animated];
     }
 
     let controller = load::<T>(this, VIEW_DELEGATE_PTR);
@@ -51,22 +48,18 @@ extern "C" fn did_disappear<T: ViewDelegate>(this: &mut Object, _: Sel, animated
 
 /// Registers an `NSViewDelegate`.
 pub(crate) fn register_view_controller_class<T: ViewDelegate + 'static>() -> *const Class {
-    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    load_or_register_class("UIViewController", "RSTViewController", |decl| unsafe {
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(UIViewController);
-        let mut decl = ClassDecl::new("RSTViewController", superclass).unwrap();
-
         decl.add_ivar::<usize>(VIEW_DELEGATE_PTR);
 
         decl.add_method(sel!(viewWillAppear:), will_appear::<T> as extern "C" fn(&mut Object, _, BOOL));
         decl.add_method(sel!(viewDidAppear:), did_appear::<T> as extern "C" fn(&mut Object, _, BOOL));
-        decl.add_method(sel!(viewWillDisappear:), will_disappear::<T> as extern "C" fn(&mut Object, _, BOOL));
+        decl.add_method(
-        decl.add_method(sel!(viewDidDisappear:), did_disappear::<T> as extern "C" fn(&mut Object, _, BOOL));
+            sel!(viewWillDisappear:),
-
+            will_disappear::<T> as extern "C" fn(&mut Object, _, BOOL)
-        VIEW_CLASS = decl.register();
+        );
-    });
+        decl.add_method(
-
+            sel!(viewDidDisappear:),
-    unsafe { VIEW_CLASS }
+            did_disappear::<T> as extern "C" fn(&mut Object, _, BOOL)
+        );
+    })
 }

src/view/uikit.rs

@@ -1,5 +1,3 @@
-use std::sync::Once;
-
 use objc::declare::ClassDecl;
 use objc::runtime::{Class, Object, Sel, BOOL};
 use objc::{class, sel, sel_impl};
@@ -14,16 +12,7 @@ use crate::view::{ViewDelegate, VIEW_DELEGATE_PTR};
 /// 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;
+    load_or_register_class("UIView", "RSTView", |decl| unsafe {})
-    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 a `UIView` subclass, with some callback and pointer ivars for what we

src/webview/class.rs

@@ -12,7 +12,7 @@ use objc::declare::ClassDecl;
 use objc::runtime::{Class, Object, Sel};
 use objc::{class, msg_send, sel, sel_impl};
 
-use crate::foundation::{id, nil, NSArray, NSInteger, NSString, NO, YES};
+use crate::foundation::{id, load_or_register_class, nil, NSArray, NSInteger, NSString, NO, YES};
 use crate::webview::actions::{NavigationAction, NavigationResponse};
 use crate::webview::{mimetype::MimeType, WebViewDelegate, WEBVIEW_DELEGATE_PTR}; //, OpenPanelParameters};
                                                                                  //use crate::webview::enums::{NavigationPolicy, NavigationResponsePolicy};
@@ -170,29 +170,14 @@ extern "C" fn handle_download<T: WebViewDelegate>(this: &Object, _: Sel, downloa
 /// both a subclass of `NSViewController` and a delegate of the held `WKWebView` (for the various
 /// varieties of delegates needed there).
 pub fn register_webview_class() -> *const Class {
-    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    load_or_register_class("WKWebView", "CacaoWebView", |decl| unsafe {})
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(WKWebView);
-        let decl = ClassDecl::new("RSTWebView", superclass).unwrap();
-        VIEW_CLASS = decl.register();
-    });
-
-    unsafe { VIEW_CLASS }
 }
 
 /// Registers an `NSViewController` that we effectively turn into a `WebViewController`. Acts as
 /// both a subclass of `NSViewController` and a delegate of the held `WKWebView` (for the various
 /// varieties of delegates needed there).
-pub fn register_webview_delegate_class<T: WebViewDelegate>() -> *const Class {
+pub fn register_webview_delegate_class<T: WebViewDelegate>(instance: &T) -> *const Class {
-    static mut VIEW_CLASS: *const Class = 0 as *const Class;
+    load_or_register_class("NSObject", instance.subclass_name(), |decl| unsafe {
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = class!(NSObject);
-        let mut decl = ClassDecl::new("RSTWebViewDelegate", superclass).unwrap();
-
         decl.add_ivar::<usize>(WEBVIEW_DELEGATE_PTR);
 
         // WKNavigationDelegate
@@ -239,9 +224,5 @@ pub fn register_webview_delegate_class<T: WebViewDelegate>() -> *const Class {
             sel!(_download:decideDestinationWithSuggestedFilename:completionHandler:),
             handle_download::<T> as extern "C" fn(&Object, _, id, id, usize)
         );
-
+    })
-        VIEW_CLASS = decl.register();
-    });
-
-    unsafe { VIEW_CLASS }
 }

src/webview/mod.rs

@@ -230,10 +230,11 @@ where
     /// Initializes a new WebView with a given `WebViewDelegate`. This enables you to respond to events
     /// and customize the view as a module, similar to class-based systems.
     pub fn with(config: WebViewConfig, delegate: T) -> WebView<T> {
+        let delegate_class = register_webview_delegate_class(&delegate);
         let mut delegate = Box::new(delegate);
 
         let objc_delegate = unsafe {
-            let objc_delegate: id = msg_send![register_webview_delegate_class::<T>(), new];
+            let objc_delegate: id = msg_send![delegate_class, new];
             let ptr: *const T = &*delegate;
             (&mut *objc_delegate).set_ivar(WEBVIEW_DELEGATE_PTR, ptr as usize);
             ShareId::from_ptr(objc_delegate)

src/webview/process_pool.rs

@@ -4,41 +4,23 @@
 //!
 //! If you use that feature, there are no guarantees you'll be accepted into the App Store.
 
-use std::sync::Once;
-use std::ffi::c_void;
-
 use block::Block;
-
+use cocoa::foundation::{NSArray, NSInteger, NSPoint, NSRect, NSSize, NSString};
-use cocoa::foundation::{NSRect, NSPoint, NSSize, NSString, NSArray, NSInteger};
-
 use objc::declare::ClassDecl;
 use objc::runtime::{Class, Object, Sel, BOOL};
 use objc::{class, msg_send, sel, sel_impl};
 
-use crate::foundation::{id, nil, YES, NO};
+use crate::foundation::{id, nil, NO, YES};
 use crate::webview::traits::WebViewController;
 
 extern "C" fn download_delegate(this: &Object, _: Sel) -> id {
     println!("YO!");
-    unsafe {
+    unsafe { NSString::alloc(nil).init_str("") }
-    NSString::alloc(nil).init_str("")
-    }
 }
 
 pub fn register_process_pool() -> *const Object {
-    static mut PROCESS_POOL: *const Object = 0 as *const Object;
+    load_or_register_class("WKProcessPool", "RSTWebViewProcessPool", |decl| unsafe {
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = Class::get("WKProcessPool").unwrap();
-        let mut decl = ClassDecl::new("RSTWebViewProcessPool", superclass).unwrap();
-
         //decl.add_ivar::<id>(DOWNLOAD_DELEGATE_PTR);
         decl.add_method(sel!(_downloadDelegate), download_delegate as extern "C" fn(&Object, _) -> id);
-
+    })
-        //PROCESS_POOL = decl.register();
-        PROCESS_POOL = msg_send![decl.register(), new];
-    });
-
-    unsafe { PROCESS_POOL }
 }

src/webview/traits.rs

@@ -8,6 +8,17 @@ use crate::webview::WebView;
 
 /// You can implement this on structs to handle callbacks from the underlying `WKWebView`.
 pub trait WebViewDelegate {
+    /// Used to cache subclass creations on the Objective-C side.
+    /// You can just set this to be the name of your delegate type. This
+    /// value *must* be unique per-type.
+    const NAME: &'static str;
+
+    /// You should rarely (read: probably never) need to implement this yourself.
+    /// It simply acts as a getter for the associated `NAME` const on this trait.
+    fn subclass_name(&self) -> &'static str {
+        Self::NAME
+    }
+
     /// Called when the View is ready to work with. You're passed a `ViewHandle` - this is safe to
     /// store and use repeatedly, but it's not thread safe - any UI calls must be made from the
     /// main thread!