ios8 - iOS 8 照片框架 : Get a list of all albums with iOS8

Question

如何在 iOS8 中获取所有收藏的列表，包括相机胶卷(现在称为时刻)？

在 iOS 7 中，我使用 ALAssetGroup 枚举 block ，但这不包括 iOS 时刻，这似乎相当于 iOS7 中的相机胶卷。

    void (^assetGroupEnumerator)(ALAssetsGroup *, BOOL *) = ^(ALAssetsGroup *group, BOOL *stop)
    {
        if (group == nil) {// We're done enumerating
            return;
        }

        [group setAssetsFilter:[ALAssetsFilter allAssets]];
        if ([[sGroupPropertyName lowercaseString] isEqualToString:@"camera roll"] && nType == ALAssetsGroupSavedPhotos) {
            [_assetGroups insertObject:group atIndex:0];
        } else {
            [_assetGroups addObject:group];
        }
    };

    // Group Enumerator Failure Block
    void (^assetGroupEnumberatorFailure)(NSError *) = ^(NSError *error) {
        SMELog(@"Enumeration occured %@", [error description]);
    };

    // Enumerate Albums
    [_library enumerateGroupsWithTypes:kSupportedALAlbumsMask
                            usingBlock:assetGroupEnumerator
                          failureBlock:assetGroupEnumberatorFailure];
    }];

Answer 1

使用 Photos Framework 有点不同，但您可以实现相同的结果，只需分批进行即可。

1)获取所有照片(iOS8中的时刻，或之前的相机胶卷)

PHFetchResult *allPhotosResult = [PHAsset fetchAssetsWithMediaType:PHAssetMediaTypeImage options:nil];

如果您希望它们按创建日期排序，您只需添加 PHFetchOptions 即可，如下所示:

PHFetchOptions *allPhotosOptions = [PHFetchOptions new];
allPhotosOptions.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:YES]];

PHFetchResult *allPhotosResult = [PHAsset fetchAssetsWithMediaType:PHAssetMediaTypeImage options:allPhotosOptions];

现在，如果您愿意，您可以从 PHFetchResult 对象获取资源:

[allPhotosResult enumerateObjectsUsingBlock:^(PHAsset *asset, NSUInteger idx, BOOL *stop) {
    NSLog(@"asset %@", asset);
}];

2) 获取所有用户相册(例如，通过附加排序仅显示至少包含一张照片的相册)

PHFetchOptions *userAlbumsOptions = [PHFetchOptions new];
userAlbumsOptions.predicate = [NSPredicate predicateWithFormat:@"estimatedAssetCount > 0"];

PHFetchResult *userAlbums = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAny options:userAlbumsOptions];

[userAlbums enumerateObjectsUsingBlock:^(PHAssetCollection *collection, NSUInteger idx, BOOL *stop) {
        NSLog(@"album title %@", collection.localizedTitle);
}];

对于从 PHFetchResult *userAlbums 返回的每个 PHAssetCollection，您可以像这样获取 PHAssets(您甚至可以限制结果仅包含照片) Assets ):

PHFetchOptions *onlyImagesOptions = [PHFetchOptions new];
onlyImagesOptions.predicate = [NSPredicate predicateWithFormat:@"mediaType = %i", PHAssetMediaTypeImage];
PHFetchResult *result = [PHAsset fetchAssetsInAssetCollection:collection options:onlyImagesOptions];

3) 获取智能相册

PHFetchResult *smartAlbums = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:nil];
[smartAlbums enumerateObjectsUsingBlock:^(PHAssetCollection *collection, NSUInteger idx, BOOL *stop) {
        NSLog(@"album title %@", collection.localizedTitle);
}];

关于智能相册需要注意的一件事是，如果无法确定estimatedAssetCount，collection.estimatedAssetCount 可能会返回NSNotFound。正如标题所示，这是估计的。如果您想确定 Assets 的数量，您必须执行获取并获取计数，例如:

PHFetchResult *assetsFetchResult = [PHAsset fetchAssetsInAssetCollection:assetCollection options:nil];

Assets 数量 = assetsFetchResult.count

Apple 有一个示例项目可以满足您的需求:

https://developer.apple.com/library/content/samplecode/UsingPhotosFramework/ExampleappusingPhotosframework.zip (您必须是注册开发者才能访问此内容)