AppDelegate、rootViewController 和presentViewController [英] AppDelegate, rootViewController and presentViewController

问题描述

我正在做 Facebook 集成教程，如果用户具有当前状态的有效令牌，我想显示我的 MainViewViewController，否则我想显示 LoginViewController.

I'm doing the Facebook integration tutorial, I want to show my MainViewViewController if the user has a valid token for the current state otherwise I want to show LoginViewController.

MainViewAppDelegate.m

MainViewAppDelegate.m

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    if (FBSession.activeSession.state == FBSessionStateCreatedTokenLoaded) {
        // To-do, show logged in view
    } else {
        // No, display the login page.
        [self showLoginView];
    }
    return YES;
}
- (void)showLoginView
{
    UIStoryboard *mainstoryboard = [UIStoryboard storyboardWithName:@"MainStoryboard"          bundle:nil];
    LoginViewController* loginViewController = [mainstoryboard      instantiateViewControllerWithIdentifier:@"LoginViewController"];
    [self.window.rootViewController presentViewController:loginViewController animated:YES completion:NULL];
}

控制台错误:

Warning: Attempt to present <LoginViewController: 0xb492fd0> on <MainViewViewController: 0xb1bd820> whose view is not in the window hierarchy!

我不想使用 NavigationController.

I don't want to use a NavigationController.

推荐答案

我遇到了同样的问题.基于对这个问题的回答，我在 presentViewController:animated:completion: 之前添加了 [self.window makeKeyAndVisible]，并为我修复了它.

I had the same issue. Based on the answer to this question, I added [self.window makeKeyAndVisible] just before presentViewController:animated:completion:, and that fixed it for me.

在你的情况下， showLoginView 变成

In your case, showLoginView becomes

- (void)showLoginView
{
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];
    LoginViewController *loginViewController = [storyboard instantiateViewControllerWithIdentifier:@"LoginViewController"];
    [self.window makeKeyAndVisible];
    [self.window.rootViewController presentViewController:loginViewController animated:YES completion:NULL];
}

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