得到视频的第一帧

- (UIImage*) thumbnailImageForVideo:(NSURL *)videoURL atTime:(NSTimeInterval)time {

    AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:videoURL options:nil];
    NSParameterAssert(asset);
    AVAssetImageGenerator *assetImageGenerator =[[AVAssetImageGenerator alloc] initWithAsset:asset];
    assetImageGenerator.appliesPreferredTrackTransform = YES;
    assetImageGenerator.apertureMode = AVAssetImageGeneratorApertureModeEncodedPixels;

    CGImageRef thumbnailImageRef = NULL;
    CFTimeInterval thumbnailImageTime = time;
    NSError *thumbnailImageGenerationError = nil;
    thumbnailImageRef = [assetImageGenerator copyCGImageAtTime:CMTimeMake(thumbnailImageTime, 60)actualTime:NULL error:&thumbnailImageGenerationError];

    if(!thumbnailImageRef)
        NSLog(@"thumbnailImageGenerationError %@",thumbnailImageGenerationError);

    UIImage*thumbnailImage = thumbnailImageRef ? [[UIImage alloc]initWithCGImage: thumbnailImageRef] : nil;

    return thumbnailImage;
}

　　然后调用该方法即可，你可以使用本地视频测试

    UIImageView *iimage = [[UIImageView alloc]initWithFrame:self.view.bounds];
    [self.view addSubview:iimage];

    NSString *path = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"pixelmator.mov"];
    NSURL *url = [NSURL fileURLWithPath:path];

  iimage.image =  [self thumbnailImageForVideo:url atTime:300];