ios7 - 当我在加载或打开时触发操作表时，ios会崩溃

Question

在 ios 6 中触发视图上的操作表确实加载工作，但现在在 ios 7 上崩溃。将其移动到 viewWillAppear 没有帮助。在视图出现后通过单击按钮触发操作表可以正常工作。为什么它现在不能在 ios 7 中运行？

现在加载视图时自动触发操作表的推荐方法是什么？

 UIActionSheet *actionSheet;
    NSString* title  = @"update your public profile picture";

    if (![UIImagePickerController isSourceTypeAvailable: UIImagePickerControllerSourceTypeCamera]) {
        actionSheet = [[UIActionSheet alloc] initWithTitle:title delegate:self cancelButtonTitle:@"Cancel" destructiveButtonTitle:nil otherButtonTitles: @"Choose Existing Photo",  nil];     
    }
    else {
        actionSheet = [[UIActionSheet alloc] initWithTitle:title delegate:self cancelButtonTitle:@"Cancel" destructiveButtonTitle:nil otherButtonTitles:@"Take Photo", @"Choose Existing Photo",  nil];   
    }

    [actionSheet showFromRect:CGRectMake(0, 0, [[UIScreen mainScreen]bounds].size.width, [[UIScreen mainScreen]bounds].size.height) inView:self.view animated:YES];