AVCapturePhotoOutput在闪光灯熄灭前捕捉图像

Question

我正在iOS 11上使用AVCapturePhotoOutput构建相机应用程序。下面我使用AVCapturePhotoSettings将flashMode设置为on并将捕获的图像返回到视图。闪光灯和照片捕捉均成功运行，但在闪光灯亮起之前拍摄照片。有没有办法将闪光灯和照片捕捉同步到闪光灯亮起时拍摄的位置？

以下是我的代码：

-(void)CapturePhoto
{
    photoSettings = [AVCapturePhotoSettings photoSettings];
    photoSettings.flashMode = AVCaptureFlashModeOn;
    [photoOutput capturePhotoWithSettings:photoSettings delegate:self];
}
-(void)captureOutput:(AVCapturePhotoOutput *) photoOutput
       didFinishProcessingPhoto:(AVCapturePhoto *) photo
       error:(NSError *)error
{
    if (error)
    {
        NSLog(@"error : %@", error.localizedDescription);
    }
    NSData *data = photo.fileDataRepresentation;
    UIImage *image = [UIImage imageWithData:data];
    NSString* snapshotResponse = @"image has been outputted!";
    NSLog(@"%@", snapshotResponse);
 }