ipad - UIPopoverController & UIImagePickerControl : "Popovers cannot be presented from a view which does not have a window"

Question

我正在尝试在我的 iPad 应用程序中显示一个 UIImagePickerControl。起初，调试器告诉我，在 iPad 上执行此操作时，我需要将其放入弹出窗口中。所以我写了下面的代码:

UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
imagePicker.delegate = self;
imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
popover = [[UIPopoverController alloc] initWithContentViewController:imagePicker];
[popover presentPopoverFromRect:CGRectMake(0.0, 0.0, 400.0, 400.0) 
                         inView:self.view
       permittedArrowDirections:UIPopoverArrowDirectionAny 
                       animated:YES];

但是，现在我收到以下错误:Termating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Popovers cannot be presented from a view which does not have a window.'

关于我应该做什么有什么建议吗？我知道 self.view 应该有一个窗口，但显然......它没有？

Answer 1

如果在加载 View 之前执行了那段代码，就会发生这种情况，因为 self.view 仍然是 nil，因此 self.view.window 也是.

是否有可能在加载 View 之前(在调用 -viewDidLoad: 之前)在 init 方法或其他地方执行此操作？