imagePickerController没有委托方法

Question

我想从PhotosAlbum中选择视频，遵循此代码，现在我可以选择视频，但不能转到委托方法：

imagePickerController:didFinishPickingMediaWithInfo:

我不知道为什么，感谢任何帮助。

UIImagePickerController*m_pPickerController = [[UIImagePickerController alloc] init];
            [m_pPickerController setEditing:NO];
            m_pPickerController.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
            m_pPickerController.delegate = self;
            m_pPickerController.mediaTypes = [[NSArray alloc] initWithObjects:(NSString *)kUTTypeMovie, nil];
            m_pPickerController.delegate = self;
            m_pPickerController.videoQuality=UIImagePickerControllerQualityTypeLow;
            [self presentViewController:m_pPickerController animated:YES completion:^{
                m_pPickerController.delegate = self;
            }];