ios 警告：尝试呈现其视图不在窗口层次结构中的 ViewController

Warning: attempt to present ViewController whose view is not in the window hierarchy

提问by Vinoy Alexander

In one of my apps, I'm calling a viewController from the application didReceiveLocalNotificationmethod. The page loads successfully, but it shows a warning as :

在我的一个应用程序中，我从该application didReceiveLocalNotification方法调用了一个 viewController 。页面加载成功，但显示如下警告：

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

My code is as follows :

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];  
}

采纳答案by Vinoy Alexander

Finally I solved that issue with the following code.

最后我用下面的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];
}

回答by hashier

Put

放

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

into a function e.g.

变成一个函数，例如

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

and then call it like this:

然后像这样调用它：

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

The problem got described hereand why does this performSelector:withObject:afterDelayfix this problem? Because the selector will not be called until the next run of the run loop. So things have time to settle down and you will just skip one run loop.

问题在这里得到了描述，为什么这可以performSelector:withObject:afterDelay解决这个问题？因为直到下一次运行循环才会调用选择器。所以事情有时间安定下来，你只需跳过一个运行循环。

回答by βhargav?

As per my assumption, I am feeling like you are trying to present myViewfrom self.viewControllerbefore self.viewControlleris attached or placed in window hierarchy. So just make sure to present myViewafter self.viewControllergets appear/attached to window.

根据我的假设，我觉得您正在尝试myView从附加或放置在窗口层次结构中self.viewController之前呈现self.viewController。因此，请确保myView在self.viewController出现/附加到窗口后呈现。

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

为什么模式视图控制器不能在 viewDidLoad 中呈现另一个？

回答by BhushanVU

it could be because the viewcontroller's view is not currently loaded in window hierarchy when VC is presented...

这可能是因为当呈现 VC 时，viewcontroller 的视图当前未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];
}

回答by Rob

I was having a similar issue, I was calling the presentViewController from within my AppDelegate.m when the application entered the foreground:

我遇到了类似的问题，当应用程序进入前台时，我从 AppDelegate.m 中调用 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];
        }
    }
}

---

---

This worked no problem as it dismisses the view controller first (regardless of what views have been pushed onto it) if it is present before presenting the Login view controller. If not then I can just present the Login view controller straight away.

这没有问题，因为如果它在呈现登录视图控制器之前存在，它首先关闭视图控制器（无论什么视图被推送到它上面）。如果没有，那么我可以直接显示登录视图控制器。

回答by LpLrich

Edge Case:

边缘情况：

Some people may find this through Google and it is worth pointing out that sometimes this error is raised if you are loading a view up as the root view controller which is not labelled as the initial view in Storyboard (& another view is) and then you load another view on top. Eg, in Log In Views which are loaded programmatically from within the applicationdidfinish...method of the App Delegate. Simply change the initial view (drag the arrow in Storyboard) to the appropriate one for your hierarchy. Esoteric, vague, but worth pointing out.

有些人可能会通过 Google 发现这一点，值得指出的是，如果您将视图加载为根视图控制器，该视图未标记为 Storyboard 中的初始视图（另一个视图是），则有时会引发此错误在顶部加载另一个视图。例如，在applicationdidfinish...App Delegate 方法中以编程方式加载的登录视图中。只需将初始视图（在 Storyboard 中拖动箭头）更改为适合您的层次结构的视图。深奥、模糊，但值得指出。

回答by Sarah Prata

For Swift 2.0I used an override for viewDidAppearwith:

因为Swift 2.0我使用了一个覆盖viewDidAppear：

let vc = self.storyboard?.instantiateViewControllerWithIdentifier("Second") as! SecondViewController

让 vc = self.storyboard?.instantiateViewControllerWithIdentifier("Second") 作为！第二个视图控制器

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

Where "Second" is storyboard ID of the SecondViewController in the identity inspector.

其中“Second”是身份检查器中 SecondViewController 的故事板 ID。

回答by Suraj Mirajkar

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];

回答by Yashesh

If your application type id UINavigationController then you can use.

如果您的应用程序类型 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]; }

Hope this will help you. All the best !!!

希望这会帮助你。祝一切顺利 ！！！