Question

在我的一个应用中，我正在使用application didReceiveLocalNotification方法调用viewController。页面加载成功，但它显示警告：

 Warning: Attempt to present <blankPageViewController: 0x1fda5190> on 
 <ViewController: 0x1fd85330> whose view is not in the window hierarchy!

我的代码如下：

 -(void) application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification {

    blankPageViewController *myView = [[blankPageViewController alloc] 
               initWithNibName:@"blankPageViewController" bundle: nil];
    myView.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
    [self.viewController presentViewController:myView animated:NO completion:nil];  
}

Answer 1

最后，我用以下代码解决了这个问题。

-(void) application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification {
       self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
       self.blankviewController = [[blankPageViewController alloc] initWithNibName:@"blankPageViewController" bundle:nil];
       self.window.rootViewController = self.blankviewController;
       [self.window makeKeyAndVisible];
}

Answer 2

把

[self.viewController presentViewController:myView animated:NO completion:nil];

进入一个函数，例如

- (void)yourNewFunction
{
    [self.viewController presentViewController:myView animated:NO completion:nil];
}

然后像这样调用它：

[self performSelector:@selector(yourNewFunction) withObject:nil afterDelay:0.0];

问题被描述为here，为什么performSelector:withObject:afterDelay解决了这个问题？因为在下一次运行循环运行之前不会调用选择器。所以事情有时间安定下来，你将跳过一个运行循环。

Answer 3

根据我的假设，我觉得您试图在myView附加self.viewController之前尝试展示self.viewController或放置在窗口层次结构中。因此，请确保在myView出现/附加到窗口后显示self.viewController。

Why can't a modal view controller present another in viewDidLoad?

Answer 4

可能是因为当VC出现时，viewcontroller的视图当前没有加载到窗口层次结构中......

-(void) application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification
{
    UINavigationController *navigationController = (UINavigationController*) self.window.rootViewController;
    rootViewController = [[navigationController viewControllers] objectAtIndex:0];
    blankPageViewController *myView = [[blankPageViewController alloc] initWithNibName:@"blankPageViewController" bundle: nil];
    [rootViewController presentModalViewController:myView animated:YES];
}

Answer 5

我遇到了类似的问题，当应用程序进入前台时，我在AppDelegate.m中调用了presentViewController：

- (void)applicationWillEnterForeground:(UIApplication *)application
{
    NSDate * lastActive = [[NSUserDefaults standardUserDefaults] objectForKey:@"lastActive"];

    double interval = [[NSDate date] timeIntervalSinceDate:lastActive];

    NSLog(@"Time Interval: %f", interval);

    if (interval > 900) { // interval is in seconds, so 900 seconds = 15 mins
        Login *pres = [self.window.rootViewController.storyboard instantiateViewControllerWithIdentifier:@"login"];

        UINavigationController *navi = ((UINavigationController*)self.window.rootViewController);
        if (navi.presentedViewController) {
            [navi dismissViewControllerAnimated:YES completion:^{
                [navi presentViewController:pres animated:NO completion:nil];
            }];
        } else {
            [navi presentViewController:pres animated:NO completion:nil];
        }
    }
}

这没有问题，因为如果在呈现Login视图控制器之前它存在，它首先解除视图控制器（无论哪个视图被推到它上）。如果没有，那么我可以立即呈现Login视图控制器。

Answer 6

Edge Case：

有些人可能会通过Google找到这一点，并且值得指出的是，如果您将视图加载为根视图控制器（有时未在Storyboard中标记为初始视图），则有时会出现此错误（＆amp;另一个视图是）然后你在顶部加载另一个视图。例如，在登录视图中，从App Delegate的applicationdidfinish...方法中以编程方式加载。只需将初始视图（将Storyboard中的箭头拖动）更改为适合您的层次结构的视图。深奥，模糊，但值得指出。

Answer 7

如果您的应用程序类型为ID UINavigationController，那么您可以使用。

-(void) application:(UIApplication *)application didReceiveLocalNotification:(UILocalNotification *)notification {

blankPageViewController *myView = [[blankPageViewController alloc]
                                   initWithNibName:@"blankPageViewController" bundle: nil];
myView.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self.navigationController presentViewController:myView animated:NO completion:nil]; }

希望这会对你有所帮助。一切顺利!!!

Answer 8

对于 Swift 2.0 ，我使用了viewDidAppear的覆盖：

让vc = self.storyboard？.instantiateViewControllerWithIdentifier（＆＃34; Second＆＃34;）为！ SecondViewController

self.presentViewController(vc, animated: true, completion: nil)

Where＆＃34; Second＆＃34;是身份检查器中SecondViewController的故事板ID。

Answer 9

I have used Navigation Controller and on which i have used a
ModalViewController to present a Popup(Present over current context). 
From this Popup i am opening a ViewController Modally which 
caused the Warning. So to resolve i did below change:

[self.presentedViewController performSegueWithIdentifier:@"PresentScreenSegueId" sender:sender];

警告：尝试呈现其视图不在窗口层次结构中的ViewController

9 个答案: