Set rootViewController iOS 13 - ios

Question

After upgrading Xcode a critical part of my application has stopped working.
When my app launches I run a function to check boolean flags and set the correct rootViewController.
But the code I have been using to set this has now stopped working
class func setLoginAsInitialViewContoller(window:UIWindow) {
print("SET LOGIN")
let storyboard = UIStoryboard(name: "Login", bundle: nil)
let controller = storyboard.instantiateViewController(withIdentifier: "LoginViewController")
controller.modalPresentationStyle = .overFullScreen
window.rootViewController = controller
window.makeKeyAndVisible()
}
Specifically when the app gets the the second last line window.rootViewController = controller it crashes with a libc++abi.dylib: terminating with uncaught exception of type NSException error.
The above function is in a class called Utilities.swift and I am calling the function from within my AppDelegate.swift as shown below:
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
var storyboard: UIStoryboard? = nil
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
UIApplication.shared.isIdleTimerDisabled = true
Utilities.decideInitialViewController(window: self.window!)
return true
}
Any solutions or fixes on how I can set the root controller is much appreciated.
Thank!

Answer 1

This is because AppDelegate doesn't have window property anymore.
Now you must use SceneDelegate's scene(_:willConnectTo:options:) method to change root view controller.
Like shown in this example:
func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
guard let scene = (scene as? UIWindowScene) else { return }
// Instantiate UIWindow with scene
let window = UIWindow(windowScene: scene)
// Assign window to SceneDelegate window property
self.window = window
// Set initial view controller from Main storyboard as root view controller of UIWindow
self.window?.rootViewController = UIStoryboard(name: "Main", bundle: nil).instantiateInitialViewController()
// Present window to screen
self.window?.makeKeyAndVisible()
}

Answer 2

It is available in SceneDelegate.swift file in your project
It will have delegate method :
func scene(_ scene: UIScene, willConnectTo session: UISceneSession,
options connectionOptions: UIScene.ConnectionOptions)
Example
func scene(_ scene: UIScene, willConnectTo session: UISceneSession,
options connectionOptions: UIScene.ConnectionOptions) {
if let windowScene = scene as? UIWindowScene {
self.window = UIWindow(windowScene: windowScene)
let initialViewController =
storyboard.instantiateViewController(withIdentifier: "FirstViewController")
self.window!.rootViewController = initialViewController
self.window!.makeKeyAndVisible()
}
}

Answer 3

In viewDidAppear you can set root:-
override func viewDidAppear(_ animated: Bool) {
print(self.view.window)
let vc = self.storyboard?.instantiateViewController(identifier: "SecondViewController") as? SecondViewController
self.view.window?.rootViewController = vc
}

Answer 4

For anyone looking to create a couple of extensions to change the root view controller and need to support both delegate types (UISceneDelegate and AppDelegate), here's a couple:
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
}
}
And if you're in need of an extension to reach the UIWindow from a ViewController with iOS12 and iOS13 Support:
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
}
}

Answer 5

If you want to use ScenceDelegate. In scene(_:willConnectTo:options:, creates a new UIWindow, sets the window’s rootViewController and makes this window the key window.
If you don't want to use ScenceDelegate, you can try to remove it by following this.