Correct way to create nswindow, using Swift and Cocoa

Question

Normally I would use this method to open a new window with a window controller

@class WindowTestController;

@interface AppDelegate : NSObject <NSApplicationDelegate> {
    IBOutlet NSWindow        *window;
    WindowTestController     *windowController;
}
    @property (weak) IBOutlet NSWindow *window;
    @property (strong) WindowTestController *windowController;

    - (IBAction) buttonClicked:(id)sender;
@end

And then

    #import "AppDelegate.h"
    #import "WindowTestController"

    @implementation AppDelegate

    @synthesize window;
    @synthesize windowController;

- (IBAction) buttonClicked:(id)sender {
    if (windowController == nil) 
           testWindow = [[WindowTestController alloc] init];
           [windowController showWindow:nil];
    }

@end

In trying to do a similar thing in swift I've got the following

import Cocoa

class AppDelegate: NSObject, NSApplicationDelegate {

    var testWindow: NSWindowController = WindowTestController(windowNibName: "Window")

    @IBOutlet var window: NSWindow

    @IBAction func buttonClicked(sender : AnyObject) {

        testWindow.showWindow(nil)
}

    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 situation as I have to set a default value for the testWindow property I'm creating an instance of WindowTestController before I need it. i.e. I don't need to do the

if (windowController == nil) 

Is this correct or is there another method that allocates the resource when required, or am I worrying about nothing?

Doing

if (windowController == nil) 
       testWindow = WindowTestController(windowNibName: "Window")
}

Without the AppDelegate property Results in the window immediately disappearing (i.e deallocated I think).

Answer 1

This might a be a job for lazy

class AppDelegate : NSApplicationDelegate {
    lazy var windowController = WindowTestController(windowNibName: "Window")

    @IBAction func buttonClicked(sender : AnyObject) {
        windowController.showWindow(sender)
    }
}

self.windowController will be neither allocated nor nil until you attempt to call it, at which time it will be inited. But not until that time.