Not getting the value in asset when loading the video from gallery using ALAssetLibrary

Question

I want to display the thumbnail of videos by using ALAssetLibrary and for displaying the video from gallery to my app , i filtered all videos from ALAssetsFilter .

But still i am getting the null value in asset of type ALAsset.

Please tell me what i am doing wrong with my code.

Appreciate for the help.

-(void)loadAssets{
ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
[library enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop) {

    [group setAssetsFilter:[ALAssetsFilter allVideos]];
    [group enumerateAssetsWithOptions:NSEnumerationReverse usingBlock:^(ALAsset *asset, NSUInteger index, BOOL *innerStop) {
              if (asset)
              {
                  dic = [[NSMutableDictionary alloc] init];
                  ALAssetRepresentation *defaultRepresentation = [asset defaultRepresentation];
                  NSString *uti = [defaultRepresentation UTI];
                  videoURL = [[asset valueForProperty:ALAssetPropertyURLs] valueForKey:uti];
                  NSString *title = [NSString stringWithFormat:@"video %d", arc4random()%100];
                  UIImage *image = [self imageFromVideoURL:videoURL];
                  [dic setValue:image forKey:@"image"];
                  [dic setValue:title forKey:@"name"];
                  [dic setValue:videoURL forKey:@"url"];
                  [allVideos addObject:asset];

              }
          }];
         [_collectionView reloadData];
     }

failureBlock:^(NSError *error)
{
    NSLog(@"error enumerating AssetLibrary groups %@\n", error);
}];
}

- (UIImage *)imageFromVideoURL:(NSURL*)videoURL
{

UIImage *image = nil;
AVAsset *asset = [[AVURLAsset alloc] initWithURL:videoURL options:nil];;
AVAssetImageGenerator *imageGenerator = [[AVAssetImageGenerator alloc] initWithAsset:asset];
imageGenerator.appliesPreferredTrackTransform = YES;

// calc midpoint time of video
Float64 durationSeconds = CMTimeGetSeconds([asset duration]);
CMTime midpoint = CMTimeMakeWithSeconds(durationSeconds/2.0, 600);

// get the image from
NSError *error = nil;
CMTime actualTime;
CGImageRef halfWayImage = [imageGenerator copyCGImageAtTime:midpoint actualTime:&actualTime error:&error];

if (halfWayImage != NULL)
{
    // cgimage to uiimage
    image = [[UIImage alloc] initWithCGImage:halfWayImage];
    [dic setValue:image forKey:@"ImageThumbnail"];//kImage
    NSLog(@"Values of dictonary==>%@", dic);
    NSLog(@"Videos Are:%@",allVideos);
    CGImageRelease(halfWayImage);
}
return image;
}

score 1 · Accepted Answer · answered Apr 18 '16 at 06:48

1

Use this code may this will help you to generate thumbnail image-- -

-(UIImage*)loadImage {



    AVURLAsset *asset = [[AVURLAsset alloc] initWithURL:self.videoURL options:nil];



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



    generate.appliesPreferredTrackTransform = YES;



    NSError *err = NULL;



    CMTime time = CMTimeMake(1, 60);



    CGImageRef imgRef = [generate copyCGImageAtTime:time actualTime:NULL error:&err];



    return [[UIImage alloc] initWithCGImage:imgRef];



}

answered Apr 18 '16 at 06:48

Rohit Khandelwal

1,778
15
23

I used this but i am getting the error :invalid attempt to access past the lifetime of its owning ALAssetsLibrary – Neha Purwar Apr 18 '16 at 06:59
1

what is your video url. You are passing AVAsset in AVAssetImageGenerator in your code. Try to pass or initialize with AVURLAsset *asset. This code works fine for me. – Rohit Khandelwal Apr 18 '16 at 07:05
1

you can also try this for your error solution -- http://stackoverflow.com/questions/22662464/alassetslibrary-invalid-or-null – Rohit Khandelwal Apr 18 '16 at 07:11
Thanx... @Dev.RK its really very useful to solving my error. – Neha Purwar Apr 18 '16 at 10:21
Thanks @NehaPurwar my pleasure.. :) – Rohit Khandelwal Apr 18 '16 at 10:23
If answer finds helpful then please mark it as accepted or vote up. So other will find it helpful. Thanks :) – Rohit Khandelwal Apr 18 '16 at 10:24

score 0 · Answer 2 · answered Apr 18 '16 at 05:59

I have Create the Thumbnail image from Video, its working for me and the code is below,

NSURL *videoURL = [info objectForKey:UIImagePickerControllerMediaURL];
            NSLog(@"store url %@",videoURL);
AVAsset *avAsset = [AVURLAsset URLAssetWithURL:videoURL options:nil];

            if ([[avAsset tracksWithMediaType:AVMediaTypeVideo] count] > 0)
            {
                AVAssetImageGenerator *imageGenerator =[AVAssetImageGenerator assetImageGeneratorWithAsset:avAsset];
                Float64 durationSeconds = CMTimeGetSeconds([avAsset duration]);
                CMTime midpoint = CMTimeMakeWithSeconds(durationSeconds/2.0, 600);
                NSError *error;
                CMTime actualTime;


                CGImageRef halfWayImage = [imageGenerator copyCGImageAtTime:kCMTimeZero actualTime:&actualTime error:&error];


                if (halfWayImage != NULL)
                {

                    NSString *actualTimeString = (NSString *)CFBridgingRelease(CMTimeCopyDescription(NULL, actualTime));
                    NSString *requestedTimeString = (NSString *)CFBridgingRelease(CMTimeCopyDescription(NULL, midpoint));
                    NSLog(@"Got halfWayImage: Asked for %@, got %@", requestedTimeString, actualTimeString);

                    UIImage *img=[UIImage imageWithCGImage:halfWayImage];

                    playButton.hidden=NO;
                    self.myimageView.image= img; //[self scaleImage:img maxWidth:(img.size.width/5) maxHeight:(img.size.height/5)];

                }

            }

Finally got the thumbnail image, hope its helpful

Actually, i want to access the thumbnail of video by using ALAssetLibrary rather than UIImagePickerController . Please suggest me through the ALAssetLibrary.@lyyappan Ravi — Neha Purwar, Apr 18 '16 at 06:41
Yes i am also using ALAssetLibrary and uiimagepickercontroller, its working for me. — Iyyappan Ravi, Apr 18 '16 at 10:05
what is the error, this code is implemented to UIImagePickerController delegate method. — Iyyappan Ravi, Apr 18 '16 at 10:33

Not getting the value in asset when loading the video from gallery using ALAssetLibrary

2 Answers2