How set rootViewController in Scene Delegate iOS 13

Question

Before changes in UIKit iOS 13 how I can set rootViewController at SceneDelegate?

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?


    @available(iOS 13.0, *)
    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        guard let _ = (scene as? UIWindowScene) else { return }

    }

Answer 1

FYI since SwiftUI doesn't use storyboards if you just make a new SwiftUI project it will give you the code; all you need to do is replace the UIHostingViewController with your desired root VC like this:

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

  var window: UIWindow?

  func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {

    if let windowScene = scene as? UIWindowScene {
        let window = UIWindow(windowScene: windowScene)
        window.rootViewController = MyRootViewController()
        self.window = window
        window.makeKeyAndVisible()
    }
  }

Answer 2

If you ever find yourself needing to access the window from the delegate (both iOS12 & iO13)to change the rootviewcontroller here's a couple of extensions I use:

   extension UIViewController {
        var appDelegate: AppDelegate {
        return UIApplication.shared.delegate as! AppDelegate
    }
    
    var sceneDelegate: SceneDelegate? {
        guard let windowScene = UIApplication.shared.connectedScenes.first as? UIWindowScene,
            let delegate = windowScene.delegate as? SceneDelegate else { return nil }
         return delegate
    }
}

extension UIViewController {
    var window: UIWindow? {
        if #available(iOS 13, *) {
            guard let windowScene = UIApplication.shared.connectedScenes.first as? UIWindowScene,
                let delegate = windowScene.delegate as? SceneDelegate, let window = delegate.window else { return nil }
                   return window
        }
        
        guard let delegate = UIApplication.shared.delegate as? AppDelegate, let window = delegate.window else { return nil }
        return window
    }
}