AppDelegate에 '창' 변수가 없습니다. - CoreData

class AppDelegate: UIResponder, UIApplicationDelegate {

    ...

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {        
        // Just leave it as it, don't change anything
    }

    ...
}

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

        ...

    rootVC.container = (UIApplication.shared.delegate as? AppDelegate)?.persistentContainer

        ...

}