从ALAssetsLibrary获取所有照片

Question

这只会从Photos中返回一些相册，而我得到的相册中包含的资产数量与Photos应用程序中的图片数量并不相同。

NSMutableArray *groups = [[NSMutableArray alloc] init];
ALAssetsLibrary *assetLibrary = [[ALAssetsLibrary alloc] init];
[assetLibrary enumerateGroupsWithTypes:ALAssetsGroupAll
    usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
      if (group) {
          [group setAssetsFilter:[ALAssetsFilter allPhotos]];
          [groups addObject:group];
      } else {
          block([groups copy], nil);
      }
    }
    failureBlock:^(NSError *error) {
      block(nil, error);
    }];

我需要做什么才能得到全部1000个？

Answer 1

就像这样

- (void)loadLibraryGroups
{
    if (self.assetsLibrary == nil) {
        _assetsLibrary = [[ALAssetsLibrary alloc] init];
    }
    if (self.groups == nil) {
        _groups = [[NSMutableArray alloc] init];
    } else {
        [self.groups removeAllObjects];
    }

    // setup our failure view controller in case enumerateGroupsWithTypes fails
    ALAssetsLibraryAccessFailureBlock failureBlock = ^(NSError *error) {

        NSString *errorMessage = nil;
        switch ([error code]) {
            case ALAssetsLibraryAccessUserDeniedError:
            case ALAssetsLibraryAccessGloballyDeniedError:
                errorMessage = @"The user has declined access to it.";
                break;
            default:
                errorMessage = @"Reason unknown.";
                break;
        }
    };

    // emumerate through our groups and only add groups that contain photos
    ALAssetsLibraryGroupsEnumerationResultsBlock listGroupBlock = ^(ALAssetsGroup *group, BOOL *stop) {

        ALAssetsFilter *onlyPhotosFilter = [ALAssetsFilter allPhotos];
        [group setAssetsFilter:onlyPhotosFilter];
        if ([group numberOfAssets] > 0)
        {
            NSLog(@"group ==> %@",group);
            [self.groups addObject:group];
        }
        else
        {
            NSLog(@"Empty Groups load all items");

            for (ALAssetsGroup *group in self.groups) {
                [self loadImageForEachGroup:group];
            }

        }
    };

    // enumerate only photos
    NSUInteger groupTypes = ALAssetsGroupAlbum | ALAssetsGroupEvent | ALAssetsGroupFaces | ALAssetsGroupSavedPhotos;
    [self.assetsLibrary enumerateGroupsWithTypes:groupTypes usingBlock:listGroupBlock failureBlock:failureBlock];

    NSLog(@"finish load groups");
}

- (void)loadImageForEachGroup:(ALAssetsGroup *)group
{
    if (!self.assets) {
        _assets = [[NSMutableArray alloc] init];
    } else {
        [self.assets removeAllObjects];
    }

    ALAssetsGroupEnumerationResultsBlock assetsEnumerationBlock = ^(ALAsset *result, NSUInteger index, BOOL *stop) {
        if (result != nil) {
            [self.assets addObject:result];
        } else {
            [self.collectionView reloadData];
        }
    };

    ALAssetsFilter *onlyPhotosFilter = [ALAssetsFilter allPhotos];
    [group setAssetsFilter:onlyPhotosFilter];
    [group enumerateAssetsUsingBlock:assetsEnumerationBlock];
}

并在集合中加载

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return self.assets.count;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"photoCell";

    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:CellIdentifier forIndexPath:indexPath];
    // Configure the cell

    // load the asset for this cell
    ALAsset *asset = self.assets[indexPath.row];
    CGImageRef thumbnailImageRef = [asset thumbnail];
    UIImage *thumbnail = [UIImage imageWithCGImage:thumbnailImageRef];

    // apply the image to the cell
    UIImageView *imageView = (UIImageView *)[cell viewWithTag:1];
    imageView.image = thumbnail;

    return cell;
}