Can fetchAssetCollectionsWithType's results be sorted when fetching smart albums?

问题

When calling fetchAssetCollectionsWithType I have no trouble getting properly sorted results for most collection types. For example:

fetchOptions = [[PHFetchOptions alloc] init];
fetchOptions.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"localizedTitle" ascending:YES],];
PHFetchResult *topLevelUserCollections = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAlbumRegular options:fetchOptions];

I get all albums sorted correctly and if I reverse the sort order I get the opposite result.

When I do the same for PHAssetCollectionTypeSmartAlbum:

PHFetchOptions *fetchOptions = [[PHFetchOptions alloc] init];
fetchOptions.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"localizedTitle" ascending:YES],];
PHFetchResult *smartAlbums = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeAny options:fetchOptions];

The results don't come back in a particular order, though it is the same order every time. Reversing the order or changing the sort descriptor to something else like "endDate" has no effect on the results. I have verified that the items in fact have the properties like this:

for (PHAssetCollection *aSmartAlbum in smartAlbums){
    NSLog(@"localizedTitle - %@, estimatedCount - %u", aSmartAlbum.localizedTitle, (int)(aSmartAlbum.estimatedAssetCount == NSNotFound ? 0 : aSmartAlbum.estimatedAssetCount));
}

This produces logs like this: localizedTitle - Videos, estimatedCount - 0 localizedTitle - Panoramas, estimatedCount - 0 localizedTitle - Time-lapse, estimatedCount - 0 localizedTitle - Slo-mo, estimatedCount - 0 localizedTitle - Bursts, estimatedCount - 0 localizedTitle - Favorites, estimatedCount - 0 localizedTitle - All Photos, estimatedCount - 0 localizedTitle - Hidden, estimatedCount - 0 localizedTitle - Recently Added, estimatedCount - 0

Has anyone gotten it to sort correctly?

I ended up basically pulling the results into an array and sorting them. I just happen to want the Camera Roll and favorites first.

    PHFetchOptions *fetchOptions = [PHFetchOptions new];
    PHFetchResult* unorderedSmart = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeAny options:fetchOptions];

    PHAssetCollection* allPhotos;
    PHAssetCollection* favorites;
    NSMutableArray* orderedSmart = [NSMutableArray array];
    for (PHAssetCollection *aSmartAlbum in unorderedSmart){
        if (aSmartAlbum.assetCollectionSubtype == PHAssetCollectionSubtypeSmartAlbumUserLibrary) {
            allPhotos = aSmartAlbum;
        }else if (aSmartAlbum.assetCollectionSubtype == PHAssetCollectionSubtypeSmartAlbumFavorites){
            favorites = aSmartAlbum;
        }else{
            [orderedSmart addObject:aSmartAlbum];
        }
    }

    [orderedSmart sortUsingComparator:^NSComparisonResult(id  _Nonnull obj1, id  _Nonnull obj2) {
        PHAssetCollection* ac1 = obj1;
        PHAssetCollection* ac2 = obj2;

        return [ac1.localizedTitle localizedCaseInsensitiveCompare:ac2.localizedTitle];
    }];

    if (favorites) {
        [orderedSmart insertObject:favorites atIndex:0];
    }
    if (allPhotos) {
        [orderedSmart insertObject:allPhotos atIndex:0];
    }

来源：https://stackoverflow.com/questions/32340880/can-fetchassetcollectionswithtypes-results-be-sorted-when-fetching-smart-albums

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ios

photokit