iOS cuts video recording into thumbnails

/**
  * Methods to obtain all thumbnails of online videos
  *
  * @param videoURL Video link address
  *
  * @return Video screenshot
  */
+ (UIImage *)ihefe_previewImageWithVideoURL:(NSURL *)videoURL
{
 AVAsset *asset = [AVAsset assetWithURL:videoURL];

 AVAssetImageGenerator *generator = [AVAssetImageGenerator assetImageGeneratorWithAsset:asset];
  = YES;

 CGImageRef img = [generator copyCGImageAtTime:CMTimeMake(1, ) actualTime:NULL error:nil];
 UIImage *image = [UIImage imageWithCGImage:img];

 CGImageRelease(img);
 return image;
}

/**
  * Methods to get all thumbnails for local videos
  *
  * @param fileurl Video link address
  *
  * @return Video screenshot
  */
+ (UIImage *)ihefe_getScreenShotImageFromVideoURL:(NSString *)fileurl
{

 UIImage *shotImage;
 //Video path URL NSURL *fileURL = [NSURL URLWithString:fileurl];

 AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:fileURL options:nil];

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

  = YES;

 CMTime time = CMTimeMakeWithSeconds(0.0, 600);

 NSError *error = nil;

 CMTime actualTime;

 CGImageRef image = [gen copyCGImageAtTime:time actualTime:&actualTime error:&error];

 shotImage = [[UIImage alloc] initWithCGImage:image];

 CGImageRelease(image);

 return shotImage;
}

/**
  * Method of obtaining a thumbnail of a certain frame of the video
  *
  * @param videoURL Video link address Frame time
  * @param time frame time
  *
  * @return Video screenshot
  */
+ (UIImage*)ihefe_thumbnailImageForVideo:(NSURL *)videoURL atTime:(NSTimeInterval)time
{
 AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:videoURL options:nil];
 NSParameterAssert(asset);
 AVAssetImageGenerator *assetImageGenerator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
  = YES;
  = 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;
}