Trying to set up the rootVC through old AppDelegate method. But it doesn't work

Question

I am using Xcode 11. I deleted the all the SceneDelegate methods and setting up the rootViewController through AppDelegate. But it doesn't push the view controller to the next. What can be wrong ?

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()
    window?.rootViewController = ViewController()

    return true
}

}

ViewController FILE

let plusPhotoButton: UIButton = {

 let btn = UIButton(type: .system)
btn.setImage(UIImage(named: "plus_photo"), for: .normal)
btn.addTarget(self, action: #selector(source), for: .touchUpInside)

 return btn

}()

@objc func source () {
    let source = SourceViewController()
    self.navigationController?.pushViewController(source, animated: true)



}

Answer 1

you have to set this window as keyWindow

class AppDelegate: UIResponder, UIApplicationDelegate {
var window: UIWindow?

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

    window = UIWindow()
    window?.rootViewController = ViewController()
    window?.makeKeyAndVisible()
    return true
}

}

Answer 2

You need to make the root a navigationController

let nav = UINavigationController(rootViewController:ViewController())
nav.isNavigationBarHidden = true
window?.rootViewController = nav

For this self.navigationController?. not to be nil and pushes the second vc

Answer 3

You can't delete the SceneDelegate and it's not needed to delete it why should you do it...

With SceneDelegate can be like this:

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

var window: UIWindow?

func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {

    guard let windowScene = (scene as? UIWindowScene) else { return }
    window = UIWindow(frame: windowScene.coordinateSpace.bounds)
    window?.windowScene = windowScene
    self.window?.rootViewController = YourViewController()
    window?.makeKeyAndVisible()
}

func sceneDidDisconnect(_ scene: UIScene) {
    // Called as the scene is being released by the system.
    // This occurs shortly after the scene enters the background, or when its session is discarded.
    // Release any resources associated with this scene that can be re-created the next time the scene connects.
    // The scene may re-connect later, as its session was not neccessarily discarded (see `application:didDiscardSceneSessions` instead).
}

func sceneDidBecomeActive(_ scene: UIScene) {
    // Called when the scene has moved from an inactive state to an active state.
    // Use this method to restart any tasks that were paused (or not yet started) when the scene was inactive.
}

func sceneWillResignActive(_ scene: UIScene) {
    // Called when the scene will move from an active state to an inactive state.
    // This may occur due to temporary interruptions (ex. an incoming phone call).
}

func sceneWillEnterForeground(_ scene: UIScene) {
    // Called as the scene transitions from the background to the foreground.
    // Use this method to undo the changes made on entering the background.
}

func sceneDidEnterBackground(_ scene: UIScene) {
    // Called as the scene transitions from the foreground to the background.
    // Use this method to save data, release shared resources, and store enough scene-specific state information
    // to restore the scene back to its current state.
}

}

Answer 4

SceneDelegate.swift

var window: UIWindow?
func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
    guard let windowScene = (scene as? UIWindowScene) else {
        return
    }
    window = UIWindow(frame: windowScene.coordinateSpace.bounds)
    window?.windowScene = windowScene
    let mainViewController = ViewController()
    let navigationController = UINavigationController(rootViewController: mainViewController)
    window?.rootViewController = navigationController
    window?.makeKeyAndVisible()
}