Display all videos from gallery to collection view by using ALAssetLibrary - ios

Question

I am trying to fetch the video list from gallery to collection view by using ALAssetLibrary.But the video doesn't display in collection view.
And getting the Error:
Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'could not dequeue a view of kind: UICollectionElementKindCell with identifier cellIdentifier - must register a nib or a class for the identifier or connect a prototype cell in a storyboard'
*** First throw call stack:
(0x2ba0749f 0x395fbc8b 0x2ba07375 0x2c6d8d7f 0x2f4cb573 0x2ef26cd1 0x580d7 0x2ef268f5 0x2ef24fc1 0x2ef20c09 0x2eec724f 0x2e8efa0d 0x2e8eb3e5 0x2e8eb26d 0x2e8eac51 0x2e8eaa55 0x2e8e492d 0x2b9cdd95 0x2b9cb453 0x2b9cb85b 0x2b9193c1 0x2b9191d3 0x32cfd0a9 0x2ef28fa1 0x6de09 0x39b7baaf)
libc++abi.dylib: terminating with uncaught exception of type NSException
Please help me to solve this.
my code is here--
Create a collection view by using this code in viewDidLoad():
self.view = [[UIView alloc]initWithFrame:[[UIScreen mainScreen]bounds]];
UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc]init];
collectionView = [[UICollectionView alloc]initWithFrame:self.view.frame collectionViewLayout:layout];
[collectionView setDataSource:self];
[collectionView setDelegate:self];
[collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:#"cellIdentifier"];
[collectionView setBackgroundColor:[UIColor whiteColor]];
[self.view addSubview:collectionView];
Load Asset like this--
loadAssets()
{
allVideos = [[NSMutableArray alloc] init];
ALAssetsLibrary *assetLibrary = [[ALAssetsLibrary alloc] init];
[assetLibrary enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop)
{
if (group)
{
[group setAssetsFilter:[ALAssetsFilter allVideos]];
[group enumerateAssetsUsingBlock:^(ALAsset *asset, NSUInteger index, BOOL *stop)
{
if (asset)
{
dic = [[NSMutableDictionary alloc] init];
ALAssetRepresentation *defaultRepresentation = [asset defaultRepresentation];
NSString *uti = [defaultRepresentation UTI];
NSURL *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;
}
-(void)viewDidAppear:(BOOL)animated
{
[self loadAssets];
}
And in collection View--
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return [allVideos count];
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
UICollectionViewCell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:#"cellIdentifier" forIndexPath:indexPath];
NSLog(#"allvideo %#", allVideos);
ALAsset *alasset = [allVideos objectAtIndex:indexPath.row];
return cell;
}