AppDelegate.swift

import Cocoa

class AppDelegate: NSObject, NSApplicationDelegate {

   let viewController = ViewController()
   let window = NSWindow(contentRect: NSMakeRect(0, 0, NSScreen.main()!.frame.size.width, NSScreen.main()!.frame.size.height), styleMask: [.titled, .closable, .miniaturizable, .resizable], backing: NSBackingStoreType.buffered, defer: false)

   func applicationDidFinishLaunching(_ aNotification: Notification) {
       viewController.view = NSView(frame: NSMakeRect(0, 0, window.frame.size.width, window.frame.size.height))
       viewController.view.wantsLayer = true
       window.contentView!.addSubview(viewController.view)
       window.makeKeyAndOrderFront(nil)
   }

}