PHFetchResult 获取所有照片并按日期排序不一致

Question

我正在尝试构建一个简单的照片选择器，目前有两个选项：最近和收藏夹。我正在做的是试图通过creationDate 获取所有照片，但是这会在我的数据源中以错误的顺序返回图像。数据源开头有几年前的照片，还有不到几分钟的照片散落在各处。我认为问题是我需要先告诉主 fetchResult 排序顺序，但我认为这是不可能的：Unsupported sort descriptor in fetch options: (creationDate, ascending, compare:

如果能提供任何帮助，我将不胜感激。代码：

@property (nonatomic, strong) NSMutableOrderedSet *recentsDataSource;
@property (nonatomic, strong) NSMutableOrderedSet *favoritesDataSource;

- (void)setup
{
    PHFetchResult *fetchResult = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum | PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAny options:nil];

    for (PHAssetCollection *sub in fetchResult)
    {
        PHFetchOptions *fetchOptions = [[PHFetchOptions alloc]init];

        fetchOptions.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:YES]];

        PHFetchResult *assetsInCollection = [PHAsset fetchAssetsInAssetCollection:sub options:fetchOptions];

        for (PHAsset *asset in assetsInCollection)
        {
            [self.recentsDataSource addObject:asset];

            if (asset.isFavorite)
            {
                [self.favoritesDataSource addObject:asset];
            }
        }
    }
}

Answer 1

这是我自己想出来的，这是我的解决方案：

- (void)setup
{
    self.recentsDataSource = [[NSMutableOrderedSet alloc]init];
    self.favoritesDataSource = [[NSMutableOrderedSet alloc]init];

    PHFetchResult *assetCollection = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum | PHAssetCollectionTypeAlbum subtype:PHAssetCollectionSubtypeAny options:nil];

    PHFetchResult *favoriteCollection = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeSmartAlbumFavorites options:nil];

    for (PHAssetCollection *sub in assetCollection)
    {
        PHFetchResult *assetsInCollection = [PHAsset fetchAssetsInAssetCollection:sub options:nil];

        for (PHAsset *asset in assetsInCollection)
        {
            [self.recentsDataSource addObject:asset];
        }
    }

    if (self.recentsDataSource.count > 0)
    {
        NSArray *array = [self.recentsDataSource sortedArrayUsingDescriptors:@[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:NO]]];

        self.recentsDataSource = [[NSMutableOrderedSet alloc]initWithArray:array];
    }

    for (PHAssetCollection *sub in favoriteCollection)
    {
        PHFetchResult *assetsInCollection = [PHAsset fetchAssetsInAssetCollection:sub options:nil];

        for (PHAsset *asset in assetsInCollection)
        {
            [self.favoritesDataSource addObject:asset];
        }
    }

    if (self.favoritesDataSource.count > 0)
    {
        NSArray *array = [self.favoritesDataSource sortedArrayUsingDescriptors:@[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:NO]]];

        self.favoritesDataSource = [[NSMutableOrderedSet alloc]initWithArray:array];
    }
}