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

Question

当我尝试在导航 Controller 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!

我已尝试通过以下代码呈现 View Controller ，

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 呈现 View Controller 。在您的情况下，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 View Controller 本身呈现一个 View Controller 。

你需要改变:

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

到:

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