Issue #34

In an iOS project, we often see this in AppDelegate

class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {

        return true

But in a Cocoa project, we see this instead

class AppDelegate: NSObject, NSApplicationDelegate {

    func applicationDidFinishLaunching(aNotification: NSNotification) {
        // Insert code here to initialize your application

    func applicationWillTerminate(aNotification: NSNotification) {
        // Insert code here to tear down your application

In this case the param is of type NSNotification

Delegate and notification

Reading Cocoa Core Competencies - Delegation

The delegate of most Cocoa framework classes is automatically registered as an observer of notifications posted by the delegating object. The delegate need only implement a notification method declared by the framework class to receive a particular notification message. Following the example above, a window object posts an NSWindowWillCloseNotification to observers but sends a windowShouldClose: message to its delegate.

So the pattern is that the delegate should strip the NS and Notification, like NSWindowWillCloseNotification to windowShouldClose: