UIViewController on a second screen

AppDelegate.swift

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        let secondStoryboard = UIStoryboard(name: "SecondScreen", bundle: nil)
        let secondScreenVC = secondStoryboard.instantiateInitialViewController() as! SecondScreenViewController
        secondScreenVC.loadViewIfNeeded()

        let secondWindow = UIWindow()
        secondWindow.addSubview(secondScreenVC.view)
        secondWindow.rootViewController = secondScreenVC

        NotificationCenter.default.addObserver(forName: UIScreen.didConnectNotification, object: nil, queue: .main) { (notification) in
            guard let secondScreen = notification.object as? UIScreen else {
                return
            }

            secondWindow.screen = secondScreen
            secondWindow.makeKeyAndVisible()
        }
        return true
    }
}