It may come from your AppDelegate. Could you show us you AppDelegate ?
Apple introduce SceneDelegate that can impact your AppDelegate. If you don’t want to use SceneDelegate, you should define the UIWindow in the AppDelegate :
var window: UIWindow?
and init your variable :
window = UIWindow(frame: UIScreen.main.bounds)
in
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool
I wish it can help you.
solved Bad: app building starts with black screen [closed]