如何将coredatastack从AppDelegate传递到没有导航控制器的视图控制器

Question

我知道通过这种方式嵌入导航控制器将coreDataStack传递给viewController的方法。

 func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    let navigationController = window!.rootViewController as! UINavigationController
    let viewController = navigationController.topViewController as! ViewController

    viewController.coreDataStack = coreDataStack
    return true
}

我想在没有导航控制器的情况下将coreDataStack传递给我的viewController，

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
    let viewController = mainStoryboard.instantiateViewControllerWithIdentifier("Home") as! Home
    viewController.coreDataStack = coreDataStack

    return true
}

然而，viewController中的coreDataStack发现是nil。 我该怎么办？

Answer 1

您的代码正在创建视图控制器的新实例，而不是引用现有实例。你应该可以使用它：

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    let viewController = window!.rootViewController as! ViewController
    viewController.coreDataStack = coreDataStack
    return true
}