CODE EXAMPLE FOR CSHARP

remove scenedelegate

import UIKit

@main
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window:UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        self.window = UIWindow(frame: UIScreen.main.bounds)
        window?.rootViewController = UIStoryboard(name: "Main", bundle: nil).instantiateInitialViewController()
        window?.makeKeyAndVisible()

        return true
    }
}