Present UIAlertView on window

Question

There are possibility that, there is custom view over my controller and on which I have to show alert. So I am using below extension to present controllers on window rather than on any UIViewController.

Extension

extension UIViewController {
    func presentControllerToWindow(){
        let win = UIWindow(frame: UIScreen.main.bounds)
        let vc = UIViewController()
        vc.view.backgroundColor = .clear
        win.rootViewController = vc
        win.windowLevel = UIWindow.Level.alert + 1
        win.makeKeyAndVisible()
        vc.present(self, animated: true, completion: nil)
    }
}

Present AlertController

let alertController = UIAlertController(title: nil, message: "Select Option", preferredStyle: .alert)

alertController.presentControllerToWindow()

Issue :

The code is working fine upto swift 4.X but in swift 5.X, alert controller appears and dismissed automatically on the other second.

GIF:

1. OpenPicker adds custom view as a subview.
2. On clicking add file, I am presenting alertcontroller.
3. Its automatically dismissed.

Edit :

I am adding my custom view like below.

extension UIView {

    func addToWindow()  {
        let window = UIApplication.shared.keyWindow!
        self.frame = window.bounds
        window.makeKeyAndVisible()
        window.windowLevel = window.windowLevel + 1
        window.addSubview(self)
    }
}

let customView = MyCustomView()
customView.addToWindow()

Now over this MyCustomView, I need to show UIAlertController

Answer 1

you have to add your UIViewController view in UIApplication keyWindow

extension UIViewController {
    func presentControllerToWindow(){
        let win = UIWindow(frame: UIScreen.main.bounds)
        let vc = UIViewController()
        vc.view.backgroundColor = .clear
        win.rootViewController = vc
        win.windowLevel = UIWindow.Level.alert + 1
        win.makeKeyAndVisible()
        UIApplication.shared.keyWindow?.addSubview(vc.view) //added
        vc.present(self, animated: true, completion: nil)
    }
}

Answer 2

I personally use the following extension to create an alert.

extension UIViewController {
  func showAlert(withTitle title: String?, message: String?) {
    let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
    let action = UIAlertAction(title: "OK", style: .cancel, handler: nil)
    alert.addAction(action)
    present(alert, animated: true, completion: nil)
  }
}

It works fine with iOS 13