iphone - 在 Storyboard加载完成之前调用应用程序 didFinishLaunchingWithOptions？

Question

我有一个在启动时实现 Facebook 登录的应用程序，使用的代码与此非常相似:Facebook Scrumptious Tutorial ， Storyboard除外。

代码的基本要点是，在应用程序启动时，应用程序委托(delegate)会检查您是否已经登录，如果已经登录，它会直接进入主视图，如果没有，它会要求主视图呈现登录 View ，以便用户可以登录。

我已经解决了我的另一个问题，通过从 View 层次结构中获取主视图，然后在 View 上调用 segue，能够告诉 Storyboard中的主视图呈现不同的 View 。一切正常，但是我还有最后一个问题要解决:

据我所知，应用程序 didFinishLaunchingWithOptions 方法应该 在 Storyboard完全加载后调用。但是在我的代码中，如果我试图告诉主视图呈现另一个 View ，它会给我一个错误，基本上说它尚未加载(警告:尝试在 < UINavigationController: 0xa28c6e0 上呈现 < QLoginViewController: 0x955c020>> 谁的 View 不在窗口层次结构中!)。

如果我告诉它在延迟后呈现 View :

[self performSelector:@selector(showLoginViewAnimated:) withObject:NO afterDelay:.001];

(其中 showLoginViewAnimated: 是告诉主视图显示登录 View 的方法)，然后它工作正常。

谁能帮我弄清楚这里出了什么问题，我该如何解决？延迟执行选择器显然是一个糟糕的解决方法，因为我永远不知道不同的设备是否可能需要更长的时间来加载 View ...

这是我的 appDelegate didFinishLaunchingWithOptions 代码:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // Override point for customization after application launch.

    self.navigationController = (UINavigationController *)self.window.rootViewController;

    // Navigation Bar Color
    [[UINavigationBar appearance] setTintColor:[UIColor colorWithRed:255.0/255.0 green:128.0/255.0 blue:60.0/255.0 alpha:1.0]];


    /* Facebook Login */    // THIS IS THE RELEVANT CODE: 
    // See if we have a valid token for the current state
    if (FBSession.activeSession.state == FBSessionStateCreatedTokenLoaded) {
        // Yes, valid token exists - open the session (don't display login page)
        [self openSession];
    } else {
        // No, valid token does not exist -  display the login page.
        if ([self.navigationController isViewLoaded]) {
            [self showLoginViewAnimated:NO];   // MY ATTEMPT TO AVOID USING THE DELAY IF POSSIBLE
        }
        else {
            [self performSelector:@selector(showLoginViewAnimated:) withObject:NO afterDelay:.001]; // Delay needed to allow for storyboard loading
        }
    }

    return YES;
}

这里是 showLoginViewAnimated: 代码:

- (void)showLoginViewAnimated:(BOOL)animated
{
    UIViewController *topViewController = [self.navigationController topViewController];
    UIViewController *presentedViewController = [topViewController presentedViewController];

    // If the login screen is not already displayed, display it. If the login screen is
    // displayed, then getting back here means the login in progress did not successfully
    // complete. In that case, notify the login view so it can update its UI appropriately.

    if (![presentedViewController isKindOfClass:[QLoginViewController class]]) {
        if (animated) {
            [topViewController performSegueWithIdentifier:@"ShowLoginViewAnimated" sender:self];
        }
        else {
            [topViewController performSegueWithIdentifier:@"ShowLoginViewStatic" sender:self];
        }
    }
    else {
        QLoginViewController *loginViewController = (QLoginViewController *)presentedViewController;
        [loginViewController loginFailed];
    }
}

在应用程序的原始 Non-Storyboard 版本中，showLoginViewAnimated: 方法不会在application didFinishLaunchingWithOptions 中调用，直到我已经手动创建了像这样的 View 所以:

self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
// Override point for customization after application launch.
self.viewController = [[MainViewController alloc] initWithNibName:@"MainViewController" bundle:nil];
self.navController = [[UINavigationController alloc] initWithRootViewController:self.viewController];

self.window.rootViewController = self.navController;
[self.window makeKeyAndVisible];

因此，在我尝试告诉他们提出新观点之前，我已经 100% 确定这些观点存在。然而，在应用程序的 Storyboard版本中，这些代码都不存在，所以我只需要相信理论上 application didFinishLaunchingWithOptions 方法在 Storyboard View 完全加载之前不会被调用 - 然而，这不会好像是这样的。也许它是异步进行的？我不知道...

有什么想法吗？感谢您的帮助!

编辑:这是教程中的原始代码，它工作得非常好 - 并且做的事情几乎完全相同，只是使用了 nib。我已经在我的代码中将 (BOOL)animated 参数添加到 showLoginView 方法，但那是为了别的东西，不会改变任何东西(我已经检查过了)。

这是原始的( Non-Storyboard )appDelegate didFinishLaunchingWithOptions 方法:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // Override point for customization after application launch.
    self.viewController = [[FBLViewController alloc] initWithNibName:@"FBLViewController" bundle:nil];
    self.navController = [[UINavigationController alloc] initWithRootViewController:self.viewController];

    self.window.rootViewController = self.navController;
    [self.window makeKeyAndVisible];


    // See if we have a valid Facebook token for the current state
    if (FBSession.activeSession.state == FBSessionStateCreatedTokenLoaded) {
        // Yes, so just open the session (this won't display any UX).
        [self openSession];
    }
    else {
        // No, display the login page.
        [self showLoginView];
    }

    return YES;
}

这是原始的( Non-Storyboard )showLoginView 方法:

- (void)showLoginView
{
    UIViewController *topViewController = [self.navController topViewController];
    UIViewController *presentedViewController = [topViewController presentedViewController];

    // IF the login screen is not already displayed, display it. If the login screen is
    // displayed, then getting back here means the login in progress did not successfully
    // complete. In that case, notify the login view so it can update its UI appropriately.

    if (![presentedViewController isKindOfClass:[FBLLoginViewController class]]) {
        FBLLoginViewController *loginViewController = [[FBLLoginViewController alloc] initWithNibName:@"FBLLoginViewController" bundle:nil];
        loginViewController.delegate = self;
        [topViewController presentViewController:loginViewController animated:NO completion:nil];
    }
    else {
        FBLLoginViewController *loginViewController = (FBLLoginViewController *)presentedViewController;
        [loginViewController loginFailed];
    }
}

Answer 1

将此行添加到 didFinishLaunchingWithOptions:

[self.window makeKeyAndVisible];

在 Facebook 登录代码之前。