uiTabBarController视图中的黑屏

Question

I hope you can help me. I do not know what I am doing wrong and I have already done many laps to the code. What I try is that when the user is authenticated it is redirected to the tabcontroller, but the view does not load (black screen load). The weird thing is that it loads the top menu in the black loading view. Attached image of the Storyboard and the supposed loaded view. Thank you very much

func application(_ application: UIApplication, 
  didFinishLaunchingWithOptions launchOptions: 
  [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

  UIApplication.shared.statusBarStyle = .lightContent  

  let storyBoard: UIStoryboard = UIStoryboard(name:"Main", bundle: Bundle.main)

  if Session.isLoggedIn {
    print("User already logged In")
    let tabBarController = storyBoard.instantiateViewController(withIdentifier: "TabBarBuyerController")
    self.window?.makeKeyAndVisible()
    self.window?.rootViewController = tabBarController
  } else {
    print("New User")
    let loginViewController = storyBoard.instantiateViewController(withIdentifier: "LoginViewController")
    self.window?.makeKeyAndVisible()
    self.window?.rootViewController = loginViewController
}

    return FBSDKApplicationDelegate.sharedInstance().application(application, didFinishLaunchingWithOptions: launchOptions) }

Main StoryBooard picture

Loaded view

Answer 1

Problem is that you not set viewController in TabBarViewController. Use Below method for show TabBarViewController in AppDelegate

 func showHeadlineTabBarViewController() {

    let storyboard = UIStoryboard(name: "Main", bundle: nil)

    let FirstViewController: UIViewController? = storyboard.instantiateViewController(withIdentifier: String(describing: FirstViewController.self))
    let FirstViewControllerNC = UINavigationController(rootViewController: FirstViewController!) 

    let secondViewController: UIViewController? = storyboard.instantiateViewController(withIdentifier: String(describing: SecondViewController.self))
    let secondViewControllerNC = UINavigationController(rootViewController: secondViewController!) 

    let tabBarController = storyBoard.instantiateViewController(withIdentifier: "TabBarBuyerController")
    tabBarController.viewControllers = [FirstViewControllerNC, secondViewControllerNC]

    window?.rootViewController = tabBarController
    window?.makeKeyAndVisible()
}