ios - PhotoKit:fetchAssetCollectionsWithLocalIdentifiers 失败

Question

以下代码通过 3 个简单步骤突出显示了该问题:

1) 获取时刻

2)缓存时刻localIdentifier

3) 使用标识符获取时刻:失败(在设备上，iOS 8.2)

- ( void )momentLocalIdTest
{
    PHFetchResult       * fetchResult;
    PHAssetCollection   * moment;
    NSString            * localIdentifier;

    fetchResult = [ PHAssetCollection fetchMomentsWithOptions: nil ];

    if( fetchResult.count == 0 )
        return;

    moment          = fetchResult.firstObject;
    localIdentifier = moment.localIdentifier;
    fetchResult     = [ PHAssetCollection fetchAssetCollectionsWithLocalIdentifiers: @[ localIdentifier ] options: nil ];

    if( fetchResult.count == 0 )
        NSLog( @"AssetCollection with localIdentifier %@ not found!!!", localIdentifier );
}

我是不是误会了什么？看起来很简单......

感谢任何帮助!

Answer 1

我也遇到了同样的问题，无法弄清楚这段代码有什么问题。我认为这个 API 很简单而且很简单(至少 8.0 到 8.4)

这是一个变通代码；您基本上必须从标识符中重新生成 PHAssetCollection 实例

PHFetchOptions *options = [PHFetchOptions new];
options.predicate = [NSPredicate predicateWithFormat:@"localIdentifier = %@", identifier];

PHAssetCollection *collection = [[PHAssetCollection fetchMomentsWithOptions:options] firstObject];
PHFetchResult *results = [PHAsset fetchAssetsInAssetCollection:collection options:nil];