Black when screen when settings initial controller programmatically - swift

Question

Could you please look at repo https://github.com/Rukomoynikov/InitialViewControllerProgrammatically and help me. Why I got an black screen when trying instantiateViewController.
This is my AppDelegate:
import UIKit
#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.
window = UIWindow.init(frame: UIScreen.main.bounds)
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let viewController = storyboard.instantiateViewController(withIdentifier: "ViewController") as! ViewController
guard window != nil else { return true }
self.window!.backgroundColor = .darkGray
self.window!.rootViewController = viewController
self.window!.makeKeyAndVisible()
return true
}
}
Couple details.
App created in last Xcode version.
iOs deployment target changed from 13 to 12.
SceneDelegate removed.
In target settings option Main Interface cleared.
In info.plist StoryBoardName and DelegateClassName also removed.

Answer 1

The problem is that, in an attempt to make the project stop using the scene delegate and use the app delegate instead, you mangled the UIApplicationSceneManifest entry in the Info.plist. Instead, you would need to delete that entry entirely. Its mere presence is what causes the scene delegate architecture to be used.
It would be better, however, to make this work for both iOS 12 using an app delegate and iOS 13 using a scene delegate (as I have described at https://stackoverflow.com/a/58405507/341994).

Answer 2

iOS 13 has moved the windows setup from AppDeleagte to SceneDelegate to support the use of (possibly multiple) scenes rather than a single window. You now have to do the setup like this:
class SceneDelegate: UIResponder, UIWindowSceneDelegate {
var window: UIWindow?
let storyboard = UIStoryboard(name: "Main", bundle: nil)
func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
guard let windowScene = scene as? UIWindowScene else { return }
let vc = storyboard.instantiateViewController (withIdentifier: "Primary") as! ViewController
window = UIWindow(windowScene: windowScene)
window?.rootViewController = vc
window?.makeKeyAndVisible()
}
}