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

Question

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?

Core Data

686

Posted by

tokizuoh

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Answer 1

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 }
    }

Posted by

Claude31

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Answer 2

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 }
    }

Posted by

Claude31

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Answer 3

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

All solved. thank you.

Posted by

tokizuoh

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

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