- (void)imagePickerController:(UIImagePickerController *)picker   didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    NSString *mediaType = [info objectForKey: UIImagePickerControllerMediaType];
    if (CFStringCompare ((__bridge CFStringRef) mediaType, kUTTypeMovie, 0) == kCFCompareEqualTo) {
        NSURL *videoUrl=(NSURL*)[info objectForKey:UIImagePickerControllerMediaURL];
        NSString *moviePath = [videoUrl path];
        //这里利用MPMoviePlayerController来获取
        MPMoviePlayerController *player = [[MPMoviePlayerController alloc]initWithContentURL:videoUrl] ;
        UIImage  *thumbnail = [player thumbnailImageAtTime:1.0 timeOption:MPMovieTimeOptionNearestKeyFrame];

        imageV.image = thumbnail;
        player = nil;//释放player

        NSString *videoCacheDir = [NSHomeDirectory() stringByAppendingPathComponent:@"Library/Caches/UploadPhoto/"];
        if (![[NSFileManager defaultManager] fileExistsAtPath:videoCacheDir]) {
            [[NSFileManager defaultManager] createDirectoryAtPath:videoCacheDir withIntermediateDirectories:YES attributes:nil error:nil];
        }
    }
    [self dismissViewControllerAnimated:YES completion:nil];
}