iOS-删除最后一张图片

   PHFetchResult *collectonResuts = [PHAssetCollection fetchAssetCollectionsWithType:PHAssetCollectionTypeSmartAlbum subtype:PHAssetCollectionSubtypeAny options:[PHFetchOptions new]] ;
    [collectonResuts enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
        PHAssetCollection *assetCollection = obj;
        if (assetCollection.assetCollectionSubtype == PHAssetCollectionSubtypeSmartAlbumUserLibrary)  {
            PHFetchOptions *options = [PHFetchOptions new];
            options.fetchLimit = 1;
            options.sortDescriptors = @[[NSSortDescriptor sortDescriptorWithKey:@"creationDate" ascending:NO]];
            PHFetchResult *assetResult = [PHAsset fetchAssetsInAssetCollection:assetCollection options:options];

            [[PHPhotoLibrary sharedPhotoLibrary] performChanges:^{
                //获取相册的最后一张照片
                if (assetResult.firstObject) {
                    [PHAssetChangeRequest deleteAssets:@[assetResult.firstObject]];
                }
            } completionHandler:^(BOOL success, NSError *error) {
                NSLog(@"Error: %@", error);
            }];
        }
    }];