AssetsLibrary不产生预期的故障

Question

我有这样的代码：

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
        [library assetForURL:albumCopy
                 resultBlock:^(ALAsset *asset)  {
                     NSLog(@"success");
                     ...
}
            failureBlock:^(NSError *error) {
                    NSLog(@"fail");
                    ...
                }];
        [library autorelease];

问题是，当我给它一个不存在的图像时，NSLog会产生：

找不到照片1000000141

成功

如果这张照片不存在的话，我怎么知道呢？

Answer 1

解决了！

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
        [library assetForURL:albumCopy
                 resultBlock:^(ALAsset *asset)  {
                     if (asset == nil) {
                         //Image not in photo library
                     }
                     else {
                     //Image in photo library
                     }
                 }
                failureBlock:^(NSError *error) {
                    //Error
                }];
        [library autorelease];