Even if it is implemented according to the document of Core Data, it does not work well.

Question

tokizuoh OP

Created Mar ’22

Replies 2

Boosts 0

Participants 2

Document

https://developer.apple.com/documentation/coredata/setting_up_a_core_data_stack

Version

> xcodebuild -version
Xcode 13.1
Build version 13A1030d

Issue

class AppDelegate: UIResponder, UIApplicationDelegate {
  
    ...
   
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // ERROR: Cannot find 'window' in scope
        if let rootVC = window?.rootViewController as? ViewController {
            rootVC.container = persistentContainer
        }
        return true
    }
}

Error message: "Cannot find 'window' in scope" I get this error and can't build. What should I do?

Should I create the window myself?

Answered by Claude31 in 708755022

Normally, you do this now in SceneDelegate.

But if you want to do it as well in AppDelegate, you need to declare:

    var window: UIWindow?   // For iOS 12 and below

In SceneDelegate, you should have:

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?

    @available(iOS 13.0, *)
    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 _ = (scene as? UIWindowScene) else { return }
    }

Boost

Answer 1

Claude31 OP

Mar ’22

Accepted Answer

Normally, you do this now in SceneDelegate.

But if you want to do it as well in AppDelegate, you need to declare:

    var window: UIWindow?   // For iOS 12 and below

In SceneDelegate, you should have:

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?

    @available(iOS 13.0, *)
    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 _ = (scene as? UIWindowScene) else { return }
    }

2

Answer 2

tokizuoh OP

Mar ’22

I thought the same! thank you. I was skeptical about the content of the document because SceneDelegate has a window.

All solved. thank you.

0