Get thumnail of a video from a URL at arbitrary time

gistfile1.txt

// import AVFoundation

- (UIImage*)thumbnailFromVideo:(NSURL *)url atTime:(float)time {
    AVAsset *asset = [AVAsset assetWithURL:url];
    
    // get 3 decimal places
    // ex: 3.39235350 --> 3.392
    float nearest = roundf(time * 1000) / 1000;
    // make CMTime from float
    // because of 3 decimal places, we use 10000 (10^4)
    // n decimal places, use 10^(n+1)
    CMTime thumbnailTime = CMTimeMake(nearest, 10000);
    
    //  Get image from the video at the given time
    AVAssetImageGenerator *imageGenerator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
    
    CGImageRef imageRef = [imageGenerator copyCGImageAtTime:thumbnailTime actualTime:NULL error:NULL];
    UIImage *thumbnail = [UIImage imageWithCGImage:imageRef];
    CGImageRelease(imageRef);
    
    return thumbnail;
}