swift - 如何在没有导航 Controller 的情况下将 coredatastack 从 AppDelegate 传递到 View Controller

Question

我知道如何将 coreDataStack 传递给 viewController，并通过这种方式嵌入导航 Controller 。

 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
}

我想将 coreDataStack 传递到我的 viewController 而不使用导航 Controller ，

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
}

但是，发现viewController中的coreDataStack为nil。我该怎么做？

Answer 1

您的代码正在创建 View Controller 的新实例，而不是引用现有实例。您应该能够使用这个:

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