Ios 图像选择器允许编辑的问题

当用户打开他们的相机时，我有这个方法。我将“允许编辑”设置为“是”，但在编辑屏幕上，方形裁剪框仅出现在iphone上，而不是iPad上。我错过了什么

- (void)useCameraRoll 
{
    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeSavedPhotosAlbum])
    {
        UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
        imagePicker.delegate = self;
        imagePicker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
        imagePicker.mediaTypes = @[(NSString *) kUTTypeImage];
        imagePicker.allowsEditing = YES;
        if ([UIDevice currentDevice].userInterfaceIdiom == UIUserInterfaceIdiomPhone)
        {
            [self presentViewController:imagePicker animated:YES completion:nil];
        }
        else
        {
            dispatch_async(dispatch_get_main_queue(), ^{

                [self setModalPresentationStyle:UIModalPresentationFormSheet];
                [self.navigationController presentViewController:imagePicker animated:YES completion:nil];
            });
        }

    }
}

和委托方法

- (void)imagePickerController:(UIImagePickerController *)picker
didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    NSString *mediaType = info[UIImagePickerControllerMediaType];

   [self dismissViewControllerAnimated:YES completion:nil];

    if ([mediaType isEqualToString:(NSString *)kUTTypeImage])
    {
        theCustomImage = info[UIImagePickerControllerEditedImage];
        [self roundedCorners];
        [self placeImage:theCustomImage];
        customImage = true;
        UIImageWriteToSavedPhotosAlbum(theCustomImage, self, @selector(image:finishedSavingWithError:contextInfo:), nil);
    }
}

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尝试删除表单页演示文稿。只是一种预感，我无法验证它是否有效。没有帮助。谢谢你的装扮