AppDelegate.swift

import UIKit

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

  var window: UIWindow?

  func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]? = nil
  ) -> Bool {
    window = UIWindow(frame: UIScreen.main.bounds)
    window!.rootViewController = UINavigationController(rootViewController: RootViewController())
    window!.makeKeyAndVisible()
    return true
  }

}