Nearing 100% coverage for API. This brings in some necessary cleanup now that we've found the right approach to all of this.

appkit/src/app/class.rs

@@ -0,0 +1,371 @@
+//! This module implements forwarding methods for standard `NSApplicationDelegate` calls. It also
+//! creates a custom `NSApplication` subclass that currently does nothing; this is meant as a hook
+//! for potential future use.
+
+use std::unreachable;
+use std::sync::Once;
+
+use cocoa::base::{id, nil, BOOL, YES, NO};
+use cocoa::foundation::{NSUInteger};
+
+use objc::{class, msg_send, sel, sel_impl};
+use objc::declare::ClassDecl;
+use objc::runtime::{Class, Object, Sel};
+
+use url::Url;
+
+use crate::app::traits::AppController;
+use crate::constants::APP_PTR;
+use crate::error::AppKitError;
+use crate::printing::PrintSettings;
+use crate::utils::str_from;
+
+/// A handy method for grabbing our `AppController` from the pointer.
+fn app<T: AppController>(this: &Object) -> &T {
+    unsafe {
+        let app_ptr: usize = *this.get_ivar(APP_PTR);
+        let app = app_ptr as *const T;
+        &*app
+    }
+}
+
+/// Fires when the Application Delegate receives a `applicationWillFinishLaunching` notification.
+extern fn will_finish_launching<T: AppController>(this: &Object, _: Sel, _: id) {
+    app::<T>(this).will_finish_launching();
+}
+
+/// Fires when the Application Delegate receives a `applicationDidFinishLaunching` notification.
+extern fn did_finish_launching<T: AppController>(this: &Object, _: Sel, _: id) {
+    app::<T>(this).did_finish_launching();
+}
+
+/// Fires when the Application Delegate receives a `applicationWillBecomeActive` notification.
+extern fn will_become_active<T: AppController>(this: &Object, _: Sel, _: id) {
+    app::<T>(this).will_become_active();
+}
+
+/// Fires when the Application Delegate receives a `applicationDidBecomeActive` notification.
+extern fn did_become_active<T: AppController>(this: &Object, _: Sel, _: id) {
+    app::<T>(this).did_become_active();
+}
+
+/// Fires when the Application Delegate receives a `applicationWillResignActive` notification.
+extern fn will_resign_active<T: AppController>(this: &Object, _: Sel, _: id) {
+    app::<T>(this).will_resign_active();
+}
+
+/// Fires when the Application Delegate receives a `applicationDidResignActive` notification.
+extern fn did_resign_active<T: AppController>(this: &Object, _: Sel, _: id) {
+    app::<T>(this).did_resign_active();
+}
+
+/// Fires when the Application Delegate receives a 'applicationShouldTerminate:` notification.
+extern fn should_terminate<T: AppController>(this: &Object, _: Sel, _: id) -> NSUInteger {
+    app::<T>(this).should_terminate().into()
+}
+
+/// Fires when the Application Delegate receives a `applicationWillTerminate:` notification.
+extern fn will_terminate<T: AppController>(this: &Object, _: Sel, _: id) {
+    app::<T>(this).will_terminate();
+}
+
+/// Fires when the Application Delegate receives a `applicationWillHide:` notification.
+extern fn will_hide<T: AppController>(this: &Object, _: Sel, _: id) {
+    app::<T>(this).will_hide();
+}
+
+/// Fires when the Application Delegate receives a `applicationDidHide:` notification.
+extern fn did_hide<T: AppController>(this: &Object, _: Sel, _: id) {
+    app::<T>(this).did_hide();
+}
+
+/// Fires when the Application Delegate receives a `applicationWillUnhide:` notification.
+extern fn will_unhide<T: AppController>(this: &Object, _: Sel, _: id) {
+    app::<T>(this).will_unhide();
+}
+
+/// Fires when the Application Delegate receives a `applicationDidUnhide:` notification.
+extern fn did_unhide<T: AppController>(this: &Object, _: Sel, _: id) {
+    app::<T>(this).did_unhide();
+}
+
+/// Fires when the Application Delegate receives a `applicationWillUpdate:` notification.
+extern fn will_update<T: AppController>(this: &Object, _: Sel, _: id) {
+    app::<T>(this).will_update();
+}
+
+/// Fires when the Application Delegate receives a `applicationDidUpdate:` notification.
+extern fn did_update<T: AppController>(this: &Object, _: Sel, _: id) {
+    app::<T>(this).did_update();
+}
+
+/// Fires when the Application Delegate receives a
+/// `applicationShouldHandleReopen:hasVisibleWindows:` notification.
+extern fn should_handle_reopen<T: AppController>(this: &Object, _: Sel, _: id, has_visible_windows: BOOL) -> BOOL {
+    match app::<T>(this).should_handle_reopen(match has_visible_windows {
+        YES => true,
+        NO => false,
+        _ => { unreachable!(); },
+    }) {
+        true => YES,
+        false => NO
+    }
+}
+
+/// Fires when the application delegate receives a `applicationDockMenu:` request.
+extern fn dock_menu<T: AppController>(_this: &Object, _: Sel, _: id) -> id {
+    nil
+}
+
+/// Fires when the application delegate receives a `application:willPresentError:` notification.
+extern fn will_present_error<T: AppController>(this: &Object, _: Sel, _: id, error: id) -> id {
+    let error = AppKitError::new(error);
+    app::<T>(this).will_present_error(*error).into_nserror()
+}
+
+/// Fires when the application receives a `applicationDidChangeScreenParameters:` notification.
+extern fn did_change_screen_parameters<T: AppController>(this: &Object, _: Sel, _: id) {
+    app::<T>(this).did_change_screen_parameters();
+}
+
+/// Fires when the application receives a `application:willContinueUserActivityWithType:`
+/// notification.
+extern fn will_continue_user_activity_with_type<T: AppController>(_this: &Object, _: Sel, _: id, activity_type: id) -> BOOL {
+    let activity = str_from(activity_type);
+    NO
+
+    /*match app::<T>(this).will_continue_user_activity_with_type(activity) {
+        true => YES,
+        false => NO
+    }*/
+}
+
+/// Fires when the application receives a `application:continueUserActivity:restorationHandler:` notification.
+extern fn continue_user_activity<T: AppController>(_this: &Object, _: Sel, _: id, _: id, _: id) -> BOOL {
+    NO
+}
+
+/// Fires when the application receives a
+/// `application:didFailToContinueUserActivityWithType:error:` message.
+extern fn failed_to_continue_user_activity<T: AppController>(_this: &Object, _: Sel, _: id, activity_type: id, error: id) {
+
+}
+
+/// Fires when the application receives a `application:didUpdateUserActivity:` message.
+extern fn did_update_user_activity<T: AppController>(_this: &Object, _: Sel, _: id, _: id) {
+
+}
+
+/// Fires when the application receives a `application:didRegisterForRemoteNotificationsWithDeviceToken:` message.
+extern fn registered_for_remote_notifications<T: AppController>(_this: &Object, _: Sel, _: id, _: id) {
+
+}
+
+/// Fires when the application receives a `application:didFailToRegisterForRemoteNotificationsWithError:` message.
+extern fn failed_to_register_for_remote_notifications<T: AppController>(_this: &Object, _: Sel, _: id, _: id) {
+
+}
+
+/// Fires when the application receives a `application:didReceiveRemoteNotification:` message.
+extern fn did_receive_remote_notification<T: AppController>(_this: &Object, _: Sel, _: id, _: id) {
+
+}
+
+/// Fires when the application receives a `application:userDidAcceptCloudKitShareWithMetadata:`
+/// message.
+extern fn accepted_cloudkit_share<T: AppController>(_this: &Object, _: Sel, _: id, _: id) {
+
+}
+
+/// Fires when the application receives an `application:openURLs` message.
+extern fn open_urls<T: AppController>(this: &Object, _: Sel, _: id, file_urls: id) {
+    app::<T>(this).open_urls(unsafe {
+        let count: usize = msg_send![file_urls, count];
+        let mut urls: Vec<Url> = Vec::with_capacity(count);
+
+        let mut index = 0;
+        loop {
+            let url: id = msg_send![file_urls, objectAtIndex:index];
+            let absolute_string: id = msg_send![url, absoluteString];
+            let uri = str_from(absolute_string);
+
+            if let Ok(u) = Url::parse(uri) {
+                urls.push(u);
+            }
+            
+            index += 1;
+            if index == count { break; }
+        }
+
+        urls
+    });
+}
+
+/// Fires when the application receives an `application:openFileWithoutUI:` message.
+extern fn open_file_without_ui<T: AppController>(this: &Object, _: Sel, _: id, file: id) -> BOOL {
+    let filename = str_from(file);
+
+    match app::<T>(this).open_file_without_ui(filename) {
+        true => YES,
+        false => NO
+    }
+}
+
+/// Fired when the application receives an `applicationShouldOpenUntitledFile:` message.
+extern fn should_open_untitled_file<T: AppController>(this: &Object, _: Sel, _: id) -> BOOL {
+    match app::<T>(this).should_open_untitled_file() {
+        true => YES,
+        false => NO
+    }
+}
+
+/// Fired when the application receives an `applicationOpenUntitledFile:` message.
+extern fn open_untitled_file<T: AppController>(this: &Object, _: Sel, _: id) -> BOOL {
+    match app::<T>(this).open_untitled_file() {
+        true => YES,
+        false => NO
+    }
+}
+
+/// Fired when the application receives an `application:openTempFile:` message.
+extern fn open_temp_file<T: AppController>(this: &Object, _: Sel, _: id, filename: id) -> BOOL {
+    let filename = str_from(filename);
+
+    match app::<T>(this).open_temp_file(filename) {
+        true => YES,
+        false => NO
+    }
+}
+
+/// Fired when the application receives an `application:printFile:` message.
+extern fn print_file<T: AppController>(this: &Object, _: Sel, _: id, file: id) -> BOOL {
+    let filename = str_from(file);
+
+    match app::<T>(this).print_file(filename) {
+        true => YES,
+        false => NO
+    }
+}
+
+/// Fired when the application receives an `application:printFiles:withSettings:showPrintPanels:`
+/// message.
+extern fn print_files<T: AppController>(this: &Object, _: Sel, _: id, files: id, settings: id, show_print_panels: BOOL) -> NSUInteger {
+    app::<T>(this).print_files(vec![], PrintSettings::default(), match show_print_panels {
+        YES => true,
+        NO => false,
+        _ => { unreachable!(); }
+    }).into()
+}
+
+/// Called when the application receives an `application:delegateHandlesKey:` message.
+/// Note: this may not fire in sandboxed applications. Apple's documentation is unclear on the
+/// matter.
+extern fn delegate_handles_key<T: AppController>(this: &Object, _: Sel, _: id, key: id) -> BOOL {
+    let key = str_from(key);
+
+    match app::<T>(this).delegate_handles_key(key) {
+        true => YES,
+        false => NO
+    }
+}
+
+/// Registers an `NSObject` application delegate, and configures it for the various callbacks and
+/// pointers we need to have.
+pub(crate) fn register_app_controller_class<T: AppController>() -> *const Class {
+    static mut DELEGATE_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("RSTAppController", superclass).unwrap();
+
+        decl.add_ivar::<usize>(APP_PTR);
+
+        // Launching Applications
+        decl.add_method(sel!(applicationWillFinishLaunching:), will_finish_launching::<T> as extern fn(&Object, _, _));
+        decl.add_method(sel!(applicationDidFinishLaunching:), did_finish_launching::<T> as extern fn(&Object, _, _));
+        
+        // Managing Active Status
+        decl.add_method(sel!(applicationWillBecomeActive:), will_become_active::<T> as extern fn(&Object, _, _));
+        decl.add_method(sel!(applicationDidBecomeActive:), did_become_active::<T> as extern fn(&Object, _, _));
+        decl.add_method(sel!(applicationWillResignActive:), will_resign_active::<T> as extern fn(&Object, _, _));
+        decl.add_method(sel!(applicationDidResignActive:), did_resign_active::<T> as extern fn(&Object, _, _));
+
+        // Terminating Applications
+        decl.add_method(sel!(applicationShouldTerminate:), should_terminate::<T> as extern fn(&Object, _, _) -> NSUInteger);
+        decl.add_method(sel!(applicationWillTerminate:), will_terminate::<T> as extern fn(&Object, _, _));
+
+        // Hiding Applications
+        decl.add_method(sel!(applicationWillHide:), will_hide::<T> as extern fn(&Object, _, _));
+        decl.add_method(sel!(applicationDidHide:), did_hide::<T> as extern fn(&Object, _, _));
+        decl.add_method(sel!(applicationWillUnhide:), will_unhide::<T> as extern fn(&Object, _, _));
+        decl.add_method(sel!(applicationDidUnhide:), did_unhide::<T> as extern fn(&Object, _, _));
+
+        // Managing Windows
+        decl.add_method(sel!(applicationWillUpdate:), will_update::<T> as extern fn(&Object, _, _));
+        decl.add_method(sel!(applicationDidUpdate:), did_update::<T> as extern fn(&Object, _, _));
+        decl.add_method(sel!(applicationShouldHandleReopen:hasVisibleWindows:), should_handle_reopen::<T> as extern fn(&Object, _, _, BOOL) -> BOOL);
+
+        // Dock Menu
+        decl.add_method(sel!(applicationDockMenu:), dock_menu::<T> as extern fn(&Object, _, _) -> id);
+
+        // Displaying Errors
+        decl.add_method(sel!(application:willPresentError:), will_present_error::<T> as extern fn(&Object, _, _, id) -> id);
+
+        // Managing the Screen
+        decl.add_method(sel!(applicationDidChangeScreenParameters:), did_change_screen_parameters::<T> as extern fn(&Object, _, _));
+
+        // User Activities
+        decl.add_method(sel!(application:willContinueUserActivityWithType:), will_continue_user_activity_with_type::<T> as extern fn(&Object, _, _, id) -> BOOL);
+        decl.add_method(sel!(application:continueUserActivity:restorationHandler:), continue_user_activity::<T> as extern fn(&Object, _, _, id, id) -> BOOL);
+        decl.add_method(sel!(application:didFailToContinueUserActivityWithType:error:), failed_to_continue_user_activity::<T> as extern fn(&Object, _, _, id, id));
+        decl.add_method(sel!(application:didUpdateUserActivity:), did_update_user_activity::<T> as extern fn(&Object, _, _, id));
+
+        // Handling push notifications
+        decl.add_method(sel!(application:didRegisterForRemoteNotificationsWithDeviceToken:), registered_for_remote_notifications::<T> as extern fn(&Object, _, _, id));
+        decl.add_method(sel!(application:didFailToRegisterForRemoteNotificationsWithError:), failed_to_register_for_remote_notifications::<T> as extern fn(&Object, _, _, id));
+        decl.add_method(sel!(application:didReceiveRemoteNotification:), did_receive_remote_notification::<T> as extern fn(&Object, _, _, id));
+
+        // CloudKit
+        decl.add_method(sel!(application:userDidAcceptCloudKitShareWithMetadata:), accepted_cloudkit_share::<T> as extern fn(&Object, _, _, id));
+
+        // Opening Files
+        decl.add_method(sel!(application:openURLs:), open_urls::<T> as extern fn(&Object, _, _, id));
+        decl.add_method(sel!(application:openFileWithoutUI:), open_file_without_ui::<T> as extern fn(&Object, _, _, id) -> BOOL);
+        decl.add_method(sel!(applicationShouldOpenUntitledFile:), should_open_untitled_file::<T> as extern fn(&Object, _, _) -> BOOL);
+        decl.add_method(sel!(applicationOpenUntitledFile:), open_untitled_file::<T> as extern fn(&Object, _, _) -> BOOL);
+        decl.add_method(sel!(application:openTempFile:), open_temp_file::<T> as extern fn(&Object, _, _, id) -> BOOL);
+
+        // Printing
+        decl.add_method(sel!(application:printFile:), print_file::<T> as extern fn(&Object, _, _, id) -> BOOL);
+        decl.add_method(sel!(application:printFiles:withSettings:showPrintPanels:), print_files::<T> as extern fn(&Object, _, id, id, id, BOOL) -> NSUInteger);
+
+        // @TODO: Restoring Application State
+        // Depends on NSCoder support, which is... welp.
+
+        // Scripting
+        decl.add_method(sel!(application:delegateHandlesKey:), delegate_handles_key::<T> as extern fn(&Object, _, _, id) -> BOOL);
+
+        DELEGATE_CLASS = decl.register();
+    });
+
+    unsafe {
+        DELEGATE_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;
+    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
+    }
+}

appkit/src/app/events.rs

@@ -1,27 +0,0 @@
-//! This module handles providing a special subclass of `NSApplication`.
-//!
-//! Now, I know what you're thinking: this is dumb.
-//!
-//! However, there are rare cases where this is beneficial, and by default we're doing nothing...
-//! so consider this a placeholder that we might use in the future for certain things.
-
-use std::sync::Once;
-
-use objc::declare::ClassDecl;
-use objc::runtime::Class;
-
-/// Used for injecting a custom NSApplication. Currently does nothing.
-pub(crate) fn register_app_class() -> *const Class {
-    static mut DELEGATE_CLASS: *const Class = 0 as *const Class;
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = Class::get("NSApplication").unwrap();
-        let decl = ClassDecl::new("RSTApplication", superclass).unwrap();
-        DELEGATE_CLASS = decl.register();
-    });
-
-    unsafe {
-        DELEGATE_CLASS
-    }
-}

appkit/src/app/mod.rs

@@ -1,32 +1,21 @@
 //! A wrapper for `NSApplicationDelegate` on macOS. Handles looping back events and providing a very janky
 //! messaging architecture.
 
-use std::sync::Once;
-
 use cocoa::base::{id, nil};
 use cocoa::appkit::{NSRunningApplication};
 
 use objc_id::Id;
-use objc::declare::ClassDecl;
+use objc::runtime::Object;
-use objc::runtime::{Class, Object, Sel};
 use objc::{class, msg_send, sel, sel_impl};
 
+mod class;
+pub mod traits;
+pub mod types;
+
 use crate::constants::APP_PTR;
 use crate::menu::Menu;
-
+use class::{register_app_class, register_app_controller_class};
-mod events;
+pub use traits::{AppController, Dispatcher};
-use events::register_app_class;
-
-pub trait Dispatcher {
-    type Message: Send + Sync;
-
-    fn on_message(&self, _message: Self::Message) {}
-}
-
-pub trait AppDelegate {
-    fn did_finish_launching(&self) {}
-    fn did_become_active(&self) {}
-}
 
 /// A wrapper for `NSApplication`. It holds (retains) pointers for the Objective-C runtime, 
 /// which is where our application instance lives. It also injects an `NSObject` subclass,
@@ -61,7 +50,7 @@ impl App {
     }
 }
 
-impl<T, M> App<T, M> where M: Send + Sync + 'static, T: AppDelegate + Dispatcher<Message = M> {
+impl<T, M> App<T, M> where M: Send + Sync + 'static, T: AppController + 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) {
@@ -97,7 +86,7 @@ impl<T, M> App<T, M> where M: Send + Sync + 'static, T: AppDelegate + Dispatcher
         let app_delegate = Box::new(delegate);
 
         let objc_delegate = unsafe {
-            let delegate_class = register_delegate_class::<T>();
+            let delegate_class = register_app_controller_class::<T>();
             let delegate: id = msg_send![delegate_class, new];
             let delegate_ptr: *const T = &*app_delegate;
             (&mut *delegate).set_ivar(APP_PTR, delegate_ptr as usize);
@@ -114,7 +103,7 @@ impl<T, M> App<T, M> where M: Send + Sync + 'static, T: AppDelegate + Dispatcher
     }
 
     /// Kicks off the NSRunLoop for the NSApplication instance. This blocks when called.
-    /// If you're wondering where to go from here... you need an `AppDelegate` that implements
+    /// If you're wondering where to go from here... you need an `AppController` that implements
     /// `did_finish_launching`. :)
     pub fn run(&self) {
         unsafe {
@@ -125,45 +114,3 @@ impl<T, M> App<T, M> where M: Send + Sync + 'static, T: AppDelegate + Dispatcher
         }
     }
 }
-
-/// Fires when the Application Delegate receives a `applicationDidFinishLaunching` notification.
-extern fn did_finish_launching<D: AppDelegate>(this: &Object, _: Sel, _: id) {
-    unsafe {
-        let app_ptr: usize = *this.get_ivar(APP_PTR);
-        let app = app_ptr as *const D;
-        (*app).did_finish_launching();
-    };
-}
-
-/// Fires when the Application Delegate receives a `applicationDidBecomeActive` notification.
-extern fn did_become_active<D: AppDelegate>(this: &Object, _: Sel, _: id) {
-    unsafe {
-        let app_ptr: usize = *this.get_ivar(APP_PTR);
-        let app = app_ptr as *const D;
-        (*app).did_become_active();
-    }
-}
-
-/// Registers an `NSObject` application delegate, and configures it for the various callbacks and
-/// pointers we need to have.
-fn register_delegate_class<D: AppDelegate>() -> *const Class {
-    static mut DELEGATE_CLASS: *const Class = 0 as *const Class;
-    static INIT: Once = Once::new();
-
-    INIT.call_once(|| unsafe {
-        let superclass = Class::get("NSObject").unwrap();
-        let mut decl = ClassDecl::new("RSTAppDelegate", superclass).unwrap();
-
-        decl.add_ivar::<usize>(APP_PTR);
-
-        // Add callback methods
-        decl.add_method(sel!(applicationDidFinishLaunching:), did_finish_launching::<D> as extern fn(&Object, _, _));
-        decl.add_method(sel!(applicationDidBecomeActive:), did_become_active::<D> as extern fn(&Object, _, _));
-
-        DELEGATE_CLASS = decl.register();
-    });
-
-    unsafe {
-        DELEGATE_CLASS
-    }
-}

appkit/src/app/traits.rs

@@ -0,0 +1,195 @@
+//! Traits that an implementing application can conform to. These aim to wrap the general
+//! lifecycles across macOS/iOS/etc, while still conforming to a Rust-ish approach.
+
+use url::Url;
+
+use crate::app::types::{TerminateResponse, PrintResponse};
+use crate::error::AppKitError;
+use crate::menu::Menu;
+use crate::printing::types::PrintSettings;
+
+pub struct CKShareMetaData;
+pub struct UserActivity;
+
+/// 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) {}
+}
+
+/// `AppController` is more or less `AppDelegate` from the Objective-C/Swift side, just named
+/// differently to fit in with the general naming scheme found within this framework. You can
+/// implement methods from this trait in order to respond to lifecycle events that the system will
+/// fire off.
+pub trait AppController {
+    /// Called right before the application will finish launching. You really, probably, want to do
+    /// your setup in `did_finish_launching` unless you're sure of what you're doing.
+    fn will_finish_launching(&self) {}
+
+    /// Fired when the application has finished launching. Unlike most other "load" lifecycle
+    /// events in this framework, you don't get a reference to an app here - if you need to call
+    /// through to your shared application, then used the `App::shared()` call.
+    fn did_finish_launching(&self) {}
+
+    /// Fired immediately before the application is about to become active.
+    fn will_become_active(&self) {}
+
+    /// Fired when the application is about to become active.
+    fn did_become_active(&self) {}
+
+    /// Fired when the application is about to resign active state.
+    fn will_resign_active(&self) {}
+
+    /// Fired when the application has resigned active state.
+    fn did_resign_active(&self) {}
+
+    /// Fired when the application is about to hide.
+    fn will_hide(&self) {}
+
+    /// Fired after the application has hidden.
+    fn did_hide(&self) {}
+
+    /// Fired when the application is about to unhide itself.
+    fn will_unhide(&self) {}
+
+    /// Fired after the application has unhidden itself.
+    fn did_unhide(&self) {}
+
+    /// Fired immediately before the application object updates its windows.
+    fn will_update(&self) {}
+
+    /// Fired immediately after the application object updates its windows.
+    fn did_update(&self) {}
+
+    /// This is fired after the `Quit` menu item has been selected, or after you've called `App::terminate()`.
+    ///
+    /// In most cases you just want `TerminateResponse::Now` here, which enables business as usual. If you need, 
+    /// though, you can cancel the termination via `TerminateResponse::Cancel` to continue something essential. If
+    /// you do this, you'll need to be sure to call `App::reply_to_termination_request()` to circle
+    /// back.
+    fn should_terminate(&self) -> TerminateResponse { TerminateResponse::Now }
+
+    /// Fired before the application terminates. You can use this to do any required cleanup.
+    fn will_terminate(&self) {}
+
+    /// Sent by the application to the delegate prior to default behavior to reopen AppleEvents.
+    ///
+    /// `has_visible_windows` indicates whether the Application object found any visible windows in your application.
+    /// You can use this value as an indication of whether the application would do anything if you return `true`.
+    ///
+    /// Return `true` if you want the application to perform its normal tasks, or `false` if you want the 
+    /// application to do nothing. The default implementation of this method returns `true`.
+    ///
+    /// Some finer points of discussion, from Apple documentation:
+    ///
+    /// These events are sent whenever the Finder reactivates an already running application because someone 
+    /// double-clicked it again or used the dock to activate it.
+    ///
+    /// For most document-based applications, an untitled document will be created.
+    ///
+    /// [Read more
+    /// here](https://developer.apple.com/documentation/appkit/nsapplicationdelegate/1428638-applicationshouldhandlereopen?language=objc)
+    fn should_handle_reopen(&self, _has_visible_windows: bool) -> bool { true }
+
+    /// Supply a dock menu for the application dynamically. The default implementation for this
+    /// method returns `None`, for no menu.
+    fn dock_menu(&self) -> Option<Menu> { None }
+
+    /// Fired before the application presents an error message to the user. If you find the error
+    /// to be... not what you want, you can take it, alter it, and return it anew. The default
+    /// implementation of this method simply returns the error as-is.
+    fn will_present_error(&self, error: AppKitError) -> AppKitError { error }
+
+    /// Fired when the screen parameters for the application have changed (e.g, the user changed
+    /// something in their settings).
+    fn did_change_screen_parameters(&self) {}
+
+    /// Fired when the user is going to continue an activity.
+    fn will_continue_user_activity(&self, _activity_type: &str) -> bool { false }
+
+    /// Fired when data for continuing an activity is available.
+    fn continue_user_activity(&self, _activity: UserActivity) -> bool { false }
+
+    /// Fired when the activity could not be continued.
+    fn did_fail_to_continue_user_activity(&self, _activity: UserActivity, _error: AppKitError) {}
+
+    /// Fired after the user activity object has been updated.
+    fn did_update_user_activity(&self, _activity: UserActivity) {}
+
+    /// Fires after the user accepted a CloudKit sharing invitation associated with your
+    /// application. 
+    fn user_accepted_cloudkit_share(&self, _share_metadata: CKShareMetaData) {}
+   
+    /// Fired when you have a list of `Url`'s to open. This is best explained by quoting the Apple
+    /// documentation verbatim:
+    ///
+    /// _"AppKit calls this method when your app is asked to open one or more URL-based resources. 
+    /// You must declare the URL types that your app supports in your `Info.plist` file using the `CFBundleURLTypes` key. 
+    /// The list can also include URLs for documents for which your app does not have an associated `NSDocument` class. 
+    /// You configure document types by adding the `CFBundleDocumentTypes` key to your Info.plist
+    /// file."
+    ///
+    /// Note that since we have this as the de-facto method of handling resource opens, the system
+    /// will _not_ call `application:openFile:` or `application:openFiles`.
+    fn open_urls(&self, _urls: Vec<Url>) { }
+
+    /// Fired when the file is requested to be opened programmatically. This is not a commonly used
+    /// or implemented method.
+    ///
+    /// According to Apple: 
+    ///
+    /// _"The method should open the file without bringing up its application’s user interface—that is, 
+    /// work with the file is under programmatic control of sender, rather than under keyboard control of the user."_
+    ///
+    /// It's unclear how supported this is in sandbox environments, so use at your own risk.
+    fn open_file_without_ui(&self, _filename: &str) -> bool { false }
+
+    /// Fired when the application is ready and able to open a temporary file.
+    /// Return `true` or `false` here depending on whether the operation was successful.
+    ///
+    /// It's your responsibility to remove the temp file.
+    fn open_temp_file(&self, _filename: &str) -> bool { false }
+
+    /// Fired before attempting to open an untitled file. Return `true` here if you want
+    /// `open_untitled_file` to be called by the system.
+    fn should_open_untitled_file(&self) -> bool { false }
+
+    /// Called when the application has asked you to open a new, untitled file.
+    /// Returns a `bool` indicating whether the file was successfully opened or not.
+    fn open_untitled_file(&self) -> bool { true }
+
+    /// Sent when the user starts up the application on the command line with the -NSPrint option.
+    /// The application terminates immediately after this method returns. For more information,
+    /// cosnult the official Apple documentation.
+    ///
+    /// (You probably never need to implement this, but we support it anyway)
+    fn print_file(&self, _filename: &str) -> bool { false }
+
+    /// Called when the user has requested to print some files.
+    ///
+    /// Returns a `PrintResponse`, indicating status of the print job. You can return
+    /// `PrintResponse::ReplyLater` if you need to do something like confirming via a popover. If
+    /// you do this, though, you must call `App::reply_to_open_or_print()` when the operation has
+    /// been completed.
+    ///
+    /// Note that macOS has a long-deprecated `printFiles:` method, which your searching may bring
+    /// up. This method really maps to `application:printFiles:withSettings:showPrintPanels:`, so
+    /// be sure to just... look there.
+    fn print_files(&self, _filenames: Vec<String>, _settings: PrintSettings, _show_panels: bool) -> PrintResponse {
+        PrintResponse::Failure
+    }
+
+    /// Fired when the occlusion state for the app has changed.
+    ///
+    /// From Apple's docs, as there's no other way to describe this better: _upon receiving this method, you can query the 
+    /// application for its occlusion state. Note that this only notifies about changes in the state of the occlusion, not 
+    /// when the occlusion region changes. You can use this method to increase responsiveness and save power by halting any 
+    /// expensive calculations that the user can not see._
+    fn occlusion_state_changed(&self) {}
+
+    /// Fired when the system wants to know whether your application, via scripting, can handle the
+    /// key specifying operations.
+    fn delegate_handles_key(&self, _key: &str) -> bool { false }
+}

appkit/src/app/types.rs

@@ -0,0 +1,60 @@
+//! Various types used at the AppController level.
+
+use cocoa::foundation::NSUInteger;
+
+/// Used for determining how an application should handle quitting/terminating.
+/// You return this in your `AppController` `should_terminate` method.
+#[derive(Copy, Clone, Debug)]
+pub enum TerminateResponse {
+    /// Proceed with termination.
+    Now,
+
+    /// App should not be terminated.
+    Cancel,
+
+    /// It might be fine to proceed with termination later. Returning this value causes 
+    /// Cocoa to run the run loop until `should_terminate()` returns `true` or `false`.
+    ///
+    /// This return value is for primarily for cases where you need to provide alerts 
+    /// in order to decide whether to quit.
+    Later
+}
+
+impl From<TerminateResponse> for NSUInteger {
+    fn from(response: TerminateResponse) -> NSUInteger {
+        match response {
+            TerminateResponse::Now => 1,
+            TerminateResponse::Cancel => 0,
+            TerminateResponse::Later => 2
+        }
+    }
+}
+
+/// Used for handling printing files. You return this in relevant `AppController` methods.
+#[derive(Copy, Clone, Debug)]
+pub enum PrintResponse {
+    /// Printing was cancelled.
+    Cancelled,
+
+    /// Printing was a success.
+    Success,
+
+    /// Printing failed.
+    Failure,
+
+    /// For when the result of printing cannot be returned immediately (e.g, if printing causes a sheet to appear).
+    /// If your method returns PrintResponse::ReplyLater it must always invoke `App::reply_to_open_or_print()` when the 
+    /// entire print operation has been completed, successfully or not.
+    ReplyLater
+}
+
+impl From<PrintResponse> for NSUInteger {
+    fn from(response: PrintResponse) -> NSUInteger {
+        match response {
+            PrintResponse::Cancelled => 0,
+            PrintResponse::Success => 1,
+            PrintResponse::Failure => 3,
+            PrintResponse::ReplyLater => 2
+        }
+    }
+}

appkit/src/error.rs

@@ -6,8 +6,9 @@
 use std::error;
 use std::fmt;
 
-use cocoa::base::id;
+use cocoa::base::{id, nil};
-use objc::{msg_send, sel, sel_impl};
+use cocoa::foundation::{NSInteger, NSString};
+use objc::{class, msg_send, sel, sel_impl};
 
 use crate::utils::str_from;
 
@@ -40,6 +41,17 @@ impl AppKitError {
             description: str_from(description).to_string()
         })
     }
+
+    /// Used for cases where we need to return an `NSError` back to the system (e.g, top-level
+    /// error handling). We just create a new `NSError` so the `AppKitError` crate can be mostly
+    /// thread safe.
+    pub fn into_nserror(self) -> id {
+        unsafe {
+            let domain = NSString::alloc(nil).init_str(&self.domain);
+            let code = self.code as NSInteger;
+            msg_send![class!(NSError), errorWithDomain:domain code:code userInfo:nil]
+        }
+    }
 }
 
 impl fmt::Display for AppKitError {

appkit/src/lib.rs

@@ -36,6 +36,7 @@ pub mod menu;
 pub mod networking;
 pub mod notifications;
 pub mod pasteboard;
+pub mod printing;
 pub mod toolbar;
 pub mod utils;
 pub mod view;
@@ -46,7 +47,7 @@ pub mod window;
 pub use url;
 
 pub mod prelude {
-    pub use crate::app::{App, AppDelegate, Dispatcher};
+    pub use crate::app::{App, AppController, Dispatcher};
     
     pub use crate::layout::LayoutConstraint;
 

appkit/src/printing/mod.rs

@@ -0,0 +1,5 @@
+//! Implements types used for printing (both configuring print jobs, as well as the act of printing
+//! itself).
+
+pub mod types;
+pub use types::*;

appkit/src/printing/types.rs

@@ -0,0 +1,4 @@
+//! Represents settings for printing items.
+
+#[derive(Copy, Clone, Debug, Default)]
+pub struct PrintSettings;