从 iPhone 检索最后几张照片

Question

了解如何通过以下链接从 iOS 设备中检索最后一张照片

How to retrieve the most recent photo from Camera Roll on iOS?

但我想检索最后 20 张左右的照片，因为我不想降低性能，也不想让用户以相反的顺序查看他们的照片

我试过了

long index = group.numberOfAssets - 2;

并以这个错误结束

由于未捕获的异常 'NSRangeException' 导致应用程序终止，原因：'*** -[NSIndexSet initWithIndexesInRange:]: Range {4294967294, 1} 超过 NSNotFound 的最大索引值 - 1'

有人可以帮忙吗？谢谢

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];

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

    [group setAssetsFilter:[ALAssetsFilter allPhotos]];

    ***long index              = group.numberOfAssets - 2;***
    [group enumerateAssetsAtIndexes:[NSIndexSet indexSetWithIndex:index]
                            options:0
                         usingBlock:^(ALAsset *alAsset, NSUInteger index, BOOL *innerStop)

Answer 1

可能是您以错误的方式枚举。 This code gets the last image

    ALAssetsGroup* group = [groups lastObject]; // get all assets groups, i think you know how to get them.
    [group enumerateAssetsAtIndexes:[NSIndexSet indexSetWithIndex:(group.numberOfAssets - 1)] options:NSEnumerationConcurrent usingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop)
     {
         if(result) {
                  // result is your needed last asset
             }

     }];