How can I update my Window via AppDelegate in macOS Cocoa?

Question

I am using ViewController for my app content, I want be able to update my app window in AppDelegate. I know that I can update my window from ViewController but for this question I want update my window from AppDelegate while ViewController is going take care of content of my app.

import Cocoa

@main
class AppDelegate: NSObject, NSApplicationDelegate {

    let window: NSWindow? = NSApp.mainWindow

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

        window?.center()
        window?.setFrameAutosaveName("Main Window")

        window?.title = "changed label"
        window?.styleMask.remove(.closable)
        window?.styleMask.remove(.fullScreen)
        window?.styleMask.remove(.miniaturizable)
        window?.makeKeyAndOrderFront(nil)
    }

}

Answer 1

Add a declaration for your view controller and then add it to the window; (example)

   var myVC = aViewController()

inside applicationDidFinishLaunching;

   window?.contentView?.addSubview(aVC.view)