如何使用ALAssetsLibrary查找每个图像的相册名称

Question

我正在使用AlAssetLibrary类来检索有关iPad内部图像的信息。 实际上你可以看到我找到了资产的像素宽度。 我现在需要找到的是每个资产的专辑名称。 因此，如果所有资产都在“相机”相册中，我需要为每个资产找到它。 我该怎么办？ 这里有我的代码。 请注意NSString assetAlbumName。 它给我一个错误。

[library enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop) {
        if (group) {

            [group setAssetsFilter:[ALAssetsFilter allPhotos]]; //search for the photos
            [group enumerateAssetsUsingBlock:^(ALAsset *asset, NSUInteger index, BOOL *stop){
                if (asset){
                    NSNumber *width = [[[asset defaultRepresentation] metadata] objectForKey:@"PixelWidth"]; //find the key with "PixelWidth" name
                    NSString *widthString = [NSString stringWithFormat:@"%@", width]; //take the value of the key

                    NSString *assetAlbumName = [asset valueForProperty:ALAssetsGroupPropertyName]; //it return to me an ALErrorInvalidProperty
                }
            }
        }
}

谢谢

Answer 1

你可以试试

 NSString *albumName = [group valueForProperty:ALAssetsGroupPropertyName];

你在干嘛

 NSString *albumName = [assets valueForProperty:ALAssetsGroupPropertyName];

Answer 2

*// 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)
    {
        [self.groups addObject:group]; //groups is NSMutableArray
    }
    else
    {
        [self.tableView performSelectorOnMainThread:@selector(reloadData) withObject:nil waitUntilDone:NO];
    }
};

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


 ALAssetsGroup *groupAsset = groups[objectIndex];
NSString *albumName = [groupAsset valueForProperty:ALAssetsGroupPropertyName];

这是apple的示例代码，将帮助您更多..

https://developer.apple.com/library/ios/samplecode/MyImagePicker/Introduction/Intro.html#//apple_ref/doc/uid/DTS40010135