How do I change the initial view controller programmatically?

July 9, 2023

I am trying to lead the user directly to the main page of my application if they are logged in (checked using user defaults).

However, it will stay at the screen I chose as the initial view controller in the storyboard no matter what. This is my didFinishLaunchingWithOptions function in the AppDelegate file:

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        FirebaseApp.configure()
        
        
        let db = Firestore.firestore()
        print(NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true))
        if UserDefaults.standard.string(forKey: "userEmail") != nil {
            self.window = UIWindow(frame: UIScreen.main.bounds)
            let storyboard = UIStoryboard(name: "Main", bundle: nil)
            let initialViewController = storyboard.instantiateViewController(withIdentifier: "TabBarController")
            let navigationController = UINavigationController(rootViewController: initialViewController)
            self.window?.rootViewController = navigationController
            self.window?.makeKeyAndVisible()

        }
        return true
    }

>Solution :

From iOS 13 on, the responsibilites of AppDelegate have been split between AppDelegate and SceneDelegate. In particular, SceneDelegate is where you want to present a UIViewController.

Remove the if block of your code from AppDelegate and add it to wilConnectTo of SceneDelegate, like this:

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

    if UserDefaults.standard.string(forKey: "userEmail") != nil {
        self.window = UIWindow(windowScene: windowScene)

        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let initialViewController = storyboard.instantiateViewController(identifier: "TabBarController")
        let navigationController = UINavigationController(rootViewController: initialViewController)
        self.window?.rootViewController = navigationController
        self.window?.makeKeyAndVisible()
    }
}