LogIn Navigation/Segue for iOS 13.2 using Firebase

Question

I am trying to implement SignIn with Google for my iOS 13.2 app using Firebase . How do I implement a segue from the LogIn Page to HomeScreen(a ViewController ) as soon as the User has signed in.

There is a method attached to AppDelegate through GIDSignInDelegate which informs us when the user has signed in. I want to segue at that point to the home screen. This code is in the AppDelegate , and I am not able to use AppDelegate's window to load from StoryBoard because of the new SceneDelegate behaviour.

func sign(_ signIn: GIDSignIn!, didSignInFor user: GIDGoogleUser!, withError error: Error!) {
        if (error == nil) {
          // Perform any operations on signed in user here.
          // ...
            print("User signed in")

            //place to perform segue
            //write code for segue here

        }
        else {
          print("\(error.localizedDescription)")
        }
        if user != nil
        {
        guard let authentication = user.authentication else { return }
          let credential = GoogleAuthProvider.credential(withIDToken: authentication.idToken,
                                                            accessToken: authentication.accessToken)
          // ...
        Auth.auth().signIn(with: credential) { (authResult, error) in
          if let error = error {
            // ...
            return
          }
          // User is signed in
          // ...          
        }
        }       
    }   

Expected result: https://stackoverflow.com/a/27136455/6311566 but this is not working in iOS 13.2

Answer 1

OLD WAY

 func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        let rootVC = window?.rootViewController

        return true
    }

This is because AppDelegate.swift doesn't have window property anymore. Now you must use SceneDelegate.swift to change root view controller. Like shown in this example:

WHAT TO DO NOW

Now, you'll be moving that code over to your app's SceneDelegate Swift file:

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

     var window: UIWindow?


    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
         // Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
         // If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
         // This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
        guard let _ = (scene as? UIWindowScene) else { return }

        // Create the root view controller as needed
        let vc = ViewController()
        let nc = UINavigationController(rootViewController: vc)

        // Create the window. Be sure to use this initializer and not the frame one.
        let win = UIWindow(windowScene: winScene) 
        win.rootViewController = nc
        win.makeKeyAndVisible()
        window = win
    }

    // ... the rest of SceneDelegate
}