获取视频预览照片

//获取视频预览照片
- (UIImage *) getPreImageByUrl:(NSURL *)mediaUrl
{
AVURLAsset *assetImage = [[AVURLAsset
alloc] initWithURL:mediaUrl
options:nil];

AVAssetImageGenerator *gen = [[AVAssetImageGenerator
alloc]
initWithAsset:assetImage];

gen.appliesPreferredTrackTransform =
YES;

CMTime time =
CMTimeMakeWithSeconds(1,
600);
CMTime actualTime;
NSError *error =
nil;
CGImageRef imageRef = [gen
copyCGImageAtTime:time
actualTime:&actualTime error:&error];
UIImage *image = [[UIImage
alloc] initWithCGImage:imageRef];
return image;
}