Completely black screen on setting initial view controller in AppDelegate - swift

Question

All I want to do is go to the login screen if the user = nil. Otherwise it goes to the main/home section of the app which consists of the Tab Bar Controller's first view controller
Here is my app delegate:
import UIKit
import Firebase
#UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
// Override point for customization after application launch.
FirebaseApp.configure()
let storyboard = UIStoryboard(name: "Main", bundle: nil)
if Auth.auth().currentUser == nil && !UserDefaults.standard.bool(forKey: "hasViewedWalkthrough") {
let initialViewController = storyboard.instantiateViewController(withIdentifier: "WalkthroughViewController") as? WalkthroughViewController
self.window?.rootViewController = initialViewController
} else if Auth.auth().currentUser == nil && UserDefaults.standard.bool(forKey: "hasViewedWalkthrough") {
let initialViewController = storyboard.instantiateViewController(withIdentifier: "loginViewController") as? LoginViewController
self.window?.rootViewController = initialViewController
} else {
let initialViewController = storyboard.instantiateViewController(withIdentifier: "homeTabBarController") as? MainTabBarViewController
self.window?.rootViewController = initialViewController
}
self.window?.makeKeyAndVisible()
return true
}
I am not able to get to the onboarding or login screen. I am always led to the main screen. I know the screens are rendering fine if I manually set them as initial view controllers in storyboard.
I have tried numerous solutions and none of them are working.
Update

Answer 1

Try this:
let storyBoard = UIStoryboard(name: "Main", bundle: nil)
let initialViewController = storyBoard.instantiateViewControllerWithIdentifier("homeTabBarController") as? TabBarViewController // whatever your swift file is called
self.window?.rootViewController = storyBoard
use that code for each statement for the if statement, obviously change the names of the view controllers to the login one respectively.

Answer 2

For people reading this in the future, iOS 13 introduced SceneDelegate and now all UI related stuff should be configured from that point.
I faced the same issue and solved it by using this code.
The custom window should be configured from here now.
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 sceneWindow = (scene as? UIWindowScene) else { return }
window = UIWindow(frame: sceneWindow.coordinateSpace.bounds)
window?.windowScene = sceneWindow
window?.makeKeyAndVisible()
if let navigationController = Storyboard.Main.initialViewController as? UINavigationController,
let viewController = navigationController.children.first as? CountriesViewController {
viewController.inject(CountriesViewModel(provider: CountryAPI(),
informTo: viewController),
navigator: CountriesNavigator(navigationController: navigationController))
window?.rootViewController = navigationController
}
}