iOS：警告 "attempt to present ViewController whose view is not in the window hierarchy"

Question

当我尝试在导航控制器上显示 ActivityController 时收到以下警告，

Attempt to present <UIActivityViewController: 0x15be1d60> on <UINavigationController: 0x14608e80> whose view is not in the window hierarchy!

我尝试通过以下代码呈现视图控制器，

UIActivityViewController * activityController = [[UIActivityViewController alloc] initWithActivityItems:activityItems applicationActivities:applicationActivities];
    activityController.excludedActivityTypes = excludeActivities;

    UIViewController *vc = self.view.window.rootViewController;
    [vc presentViewController: activityController animated: YES completion:nil];

    [activityController setCompletionHandler:^(NSString *activityType, BOOL completed) {
        NSLog(@"completed");

    }];

这里出了什么问题？

Answer 1

您正在尝试从 rootViewController 显示视图控制器。在你的情况下，我认为 rootViewController 不是当前的 ViewController。您在其上展示或推送了一个新的 UIViewController。您应该从最顶层的视图控制器本身呈现一个视图控制器。

您需要更改：

UIViewController *vc = self.view.window.rootViewController;
[vc presentViewController: activityController animated: YES completion:nil];

至：

[self presentViewController: activityController animated: YES completion:nil];

Answer 2

分析：因为目前模态视图ViewControllerclass还没有加载到window。这就相当于盖楼了，二楼没盖，直接去盖三楼，这个肯定不行。仅在加载 ViewController 的视图后；

Python

- (void)viewDidAppear:(BOOL)animated {

 [super viewDidAppear:animated];

    [self showAlertViewController];

}

- (void)showAlertViewController {

    UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Hello world" message:@"(* ￣3)(ε￣ *)d" preferredStyle:UIAlertControllerStyleAlert];

    // Create the actions.

    UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"hello" style:UIAlertActionStyleCancel handler:^(UIAlertAction *action) {
        NSLog(@"The \"Okay/Cancel\" alert's cancel action occured.");
    }];

    UIAlertAction *otherAction = [UIAlertAction actionWithTitle:@"world" style:UIAlertActionStyleDefault handler:^(UIAlertAction *action) {
        NSLog(@"The \"Okay/Cancel\" alert's other action occured.");
    }];

    // Add the actions.
    [alertController addAction:cancelAction];
    [alertController addAction:otherAction];

    UIWindow *windows = [[UIApplication sharedApplication].delegate window];
    UIViewController *vc = windows.rootViewController;
    [vc presentViewController:alertController animated: YES completion:nil];
}

这对我有用。

Answer 3

替换行：

UIViewController *vc = self.view.window.rootViewController;
[vc presentViewController: activityController animated: YES completion:nil];
//to
[self presentViewController:activityController animated: YES completion:nil];

或

[self.navigationController pushViewController:activityController animated:YES];

Answer 4

我在 iPhone 6+ 中遇到过类似的问题。

在Swift 2.0

let obj = self.storyboard?.instantiateViewControllerWithIdentifier("navChatController") as! UINavigationController
obj.modalPresentationStyle = .FormSheet
obj.modalTransitionStyle = .CoverVertical

Constants.APPDELEGATE.window?.rootViewController?.presentViewController(obj, animated: false, completion: nil)

我是这样解决的

iOS：警告 "attempt to present ViewController whose view is not in the window hierarchy"

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

objective-c

ios

uiview-hierarchy

uiactivityviewcontroller

presentviewcontroller