我尝试使用以下代码使用
- ViewDidLoad():从照片库获取所有视频
ALAsset
从照片库中获取所有视频。现在,我想将所有视频显示到UICollectionview
上,但似乎没有显示任何内容。请给我一些建议。提前致谢。- ViewDidLoad():从照片库获取所有视频
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:dic];
[_collectionView reloadData];
}
}];
}
}
failureBlock:^(NSError *error)
{
NSLog(@"error enumerating AssetLibrary groups %@\n", error);
}];
-imageFromVideoURL():
- (UIImage *)imageFromVideoURL:(NSURL*)videoURL
{
// result
UIImage *image = nil;
// AVAssetImageGenerator
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:@"name"];
NSLog(@"Values of dictionary==>%@", dic);
NSLog(@"Videos Are:%@",videoURL);
CGImageRelease(halfWayImage);
}
return image;
}
开始在UICollectionView中显示所有视频缩略图:
- (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;
}