代碼不能在窗口層次結構的根視圖

Question

我現在面臨一個問題想我UIViewController鏈接，但我得到了我最後的錯誤。

Attempt to present ViewController whose view is not in the window hierarchy 

這裏是我的代碼：

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex 
{ 
    NSString *title = [alertView buttonTitleAtIndex:buttonIndex]; 

    if([title isEqualToString:@"Wokay"]) 
    { 
     UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil]; 
     UIViewController *vc = [storyboard instantiateViewControllerWithIdentifier:@"Vibes"]; 
     [self.window.rootViewController presentViewController:vc animated:YES completion:nil]; 

    } 
} 

代碼錯誤：

Warning: Attempt to present <ViewController: 0x110634bc0> on <Login: 0x10951e7f0> whose view is not in the window hierarchy! 

Answer 1

好像你UIViewController（Login）是不是在窗口層次。

你可能會增加您的LoginViewController作爲一個UIWindow子視圖。 如果是這樣，將其設置爲UIWindow的rootViewController

AppDelegate.m

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{ 

    //Other code parts 

    [self.window setRootViewController:loginViewController]; 
    return YES; 
} 

OR

如果要添加LoginViewController的視圖子視圖中的任何UIViewController中（比如說FirstViewController） ，目前它代替

在你FirstViewController.m，

-(void)viewDidLoad{ 
    [super viewDidLoad]; 


    LoginViewController *loginViewController ;//Instantiate LoginViewController here 
    [self presentViewController:loginViewController animated:NO completion:Nil]; 
}