iOS：截图展示ipad视频

我试图拍摄播放视频的截图，但截图总是显示空白。这是我的代码：

UIGraphicsBeginImageContext(self.view.bounds.size);
    [self.view.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    NSData *data = UIImageJPEGRepresentation(viewImage, 1.0);
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsPath = [paths objectAtIndex:0];
    NSString *filePath = [documentsPath stringByAppendingPathComponent:@"image.jpg"];
    [data writeToFile:filePath atomically:YES];

我正在使用AVPlayer/AVPlayerLayer来播放视频

你们谁知道为什么会这样？或者，如果我需要做一些特殊的视频，以便能够采取截图

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非常感谢您的帮助。

我找到了解决问题的方法：

AVAssetImageGenerator *imageGenerator = [AVAssetImageGenerator assetImageGeneratorWithAsset:[self.player.currentItem asset]];
    CGImageRef ref = [imageGenerator copyCGImageAtTime:self.player.currentItem.currentTime actualTime:nil error:nil];
    UIImage *viewImage = [UIImage imageWithCGImage:ref];
    CGImageRelease(ref);
    NSData *data = UIImageJPEGRepresentation(viewImage, 1.0);
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsPath = [paths objectAtIndex:0];
    NSString *filePath = [documentsPath stringByAppendingPathComponent:@"image.jpg"];
    [data writeToFile:filePath atomically:YES];

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它显示了除了视频以外的一切