In macOS application development, NSWindowDelegate is an essential protocol that allows developers to manage and respond to events in an NSWindow object. This is particularly important for creating responsive and interactive macOS applications. By implementing NSWindowDelegate methods, developers can handle window resizing, closing, minimizing, and other window-related events effectively. This article will guide you through the process of implementing NSWindowDelegate in your macOS applications using Swift.

Examples:

Step 1: Create a New macOS Project

1. Open Xcode and create a new macOS project.
2. Choose "App" under the macOS tab and click "Next."
3. Provide a project name, organization name, and other details, then click "Next."
4. Select a location to save your project and click "Create."

Step 2: Implement NSWindowDelegate

1. Open the AppDelegate.swift file.

2. Import the Cocoa framework if it is not already imported:

   import Cocoa

3. Make the AppDelegate class conform to the NSWindowDelegate protocol:

   @main
   class AppDelegate: NSObject, NSApplicationDelegate, NSWindowDelegate {
       var window: NSWindow!
   
       func applicationDidFinishLaunching(_ aNotification: Notification) {
           // Create the main window
           window = NSWindow(
               contentRect: NSMakeRect(0, 0, 800, 600),
               styleMask: [.titled, .closable, .resizable, .miniaturizable],
               backing: .buffered, defer: false)
           window.center()
           window.title = "NSWindowDelegate Example"
           window.makeKeyAndOrderFront(nil)
   
           // Set the window's delegate
           window.delegate = self
       }
   
       func applicationWillTerminate(_ aNotification: Notification) {
           // Insert code here to tear down your application
       }
   
       // NSWindowDelegate methods
       func windowWillClose(_ notification: Notification) {
           print("Window will close")
       }
   
       func windowDidResize(_ notification: Notification) {
           print("Window did resize")
       }
   }

Step 3: Run the Application

1. Build and run your application by clicking the "Run" button in Xcode or pressing Cmd + R.
2. Observe the console output when you resize or close the window. You should see messages indicating that the window is resizing or closing.

Additional NSWindowDelegate Methods

Here are a few more methods you can implement to handle different window events:

• func windowDidBecomeKey(_ notification: Notification) – Called when the window becomes the key window.
• func windowDidResignKey(_ notification: Notification) – Called when the window resigns its key status.
• func windowDidMiniaturize(_ notification: Notification) – Called when the window is minimized.
• func windowDidDeminiaturize(_ notification: Notification) – Called when the window is restored from a minimized state.

Example:

func windowDidBecomeKey(_ notification: Notification) {
    print("Window did become key")
}

func windowDidResignKey(_ notification: Notification) {
    print("Window did resign key")
}

func windowDidMiniaturize(_ notification: Notification) {
    print("Window did miniaturize")
}

func windowDidDeminiaturize(_ notification: Notification) {
    print("Window did deminiaturize")
}

By implementing these methods, you can effectively manage and respond to various window events, enhancing the user experience of your macOS applications.