Question

在swift中是新手，我正在尝试使用storyboard转到使用以下代码的LoginController

var window: UIWindow?

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool
{

    var type = UIUserNotificationType.Badge | UIUserNotificationType.Alert | UIUserNotificationType.Sound;
    var setting = UIUserNotificationSettings(forTypes: type, categories: nil);
    UIApplication.sharedApplication().registerUserNotificationSettings(setting);
    UIApplication.sharedApplication().registerForRemoteNotifications();

    var navCtrl =  UINavigationController();
    var isLoggedIn = NSUserDefaults.standardUserDefaults().boolForKey(USERDEFAULT_ISLOGGEDIN);
    if(isLoggedIn)
    {
        let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
        var mainController: CategoriesController = mainStoryboard.instantiateViewControllerWithIdentifier(SEGUE_CATEGORIES) as CategoriesController
        navCtrl.pushViewController(mainController, animated: true);
    }
    else
    {
        let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
        var mainController: LoginController = mainStoryboard.instantiateViewControllerWithIdentifier(SEGUE_LOGIN) as LoginController
        navCtrl.pushViewController(mainController, animated: true);
    }

    self.window?.rootViewController = navCtrl;
    self.window?.makeKeyAndVisible();

    return true
}

然而它只是显示空白屏幕。将navController指定为rootViewController有什么问题？

Answer 1

您尚未创建窗口，因此self.window将为零。仅当您从xib或故事板启动应用程序时，系统才会创建窗口。如果你不使用这些，你必须自己创建它。

由于你使用?有条件地打开了navCtrl的分配，并且对makeKeyAndVisible（）的调用根本不会被解释。

在使用之前简单地创建一个UIWindow：

func application(application: UIApplication!, didFinishLaunchingWithOptions launchOptions: NSDictionary!) -> Bool {
    self.window = UIWindow(frame: UIScreen.mainScreen().bounds)
    // ...
    self.window!.rootViewController = navCtrl;
    self.window!.makeKeyAndVisible();
    return true
}

我建议将window与!的所有来电解包。没有窗口应该是一个错误。

Answer 2

试试这种方式。我认为在设置其根ViewController之前，你无法推送UINavigationController。

var navCtrl
let isLoggedIn = NSUserDefaults.standardUserDefaults().boolForKey(USERDEFAULT_ISLOGGEDIN);
if (isLoggedIn)
{
    let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
    var mainController: CategoriesController = mainStoryboard.instantiateViewControllerWithIdentifier(SEGUE_CATEGORIES) as CategoriesController

    navCtrl = UINavigationController(rootViewController:mainController)
}
else
{
    let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
    var mainController: LoginController = mainStoryboard.instantiateViewControllerWithIdentifier(SEGUE_LOGIN) as LoginController
    navCtrl = UINavigationController(rootViewController:mainController)
}

无法在swift中作为rootViewController从Storyboard实例化viewController

2 个答案: