相关疑难解决方法(0)

刚开始使用Xcode 4.5,我在控制台中遇到了这个错误:

警告:尝试在<ViewController:0x1ec3e000>上显示<finishViewController:0x1e56e0a0>,其视图不在窗口层次结构中!

该视图仍在呈现中,应用程序中的所有内容都正常运行.这是iOS 6中的新功能吗？

这是我用来在视图之间切换的代码:

UIStoryboard *storyboard = self.storyboard;
finishViewController *finished = 
[storyboard instantiateViewControllerWithIdentifier:@"finishViewController"];

[self presentViewController:finished animated:NO completion:NULL];

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

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.