ios – ALAssetPrivate超过其拥有的ALAssetsLibrary的生命周期

我正在尝试@L_618_0@photos.app中的所有图像,并将它们显示在UICollectionView中.我有这个代码检索图像：

ALAssetsLibrary *al = [ViewController defaultAssetsLibrary];

ALAssetsGroupEnumerationResultsBlock groupEnumerAtion = ^(ALAsset *result,NSUInteger index,BOOL *stop){

    if (result!=NULL) {

        if ([[result valueForProperty:ALAssetPropertyType] isEqualToString:ALAssetTypePhoto]) {

            [imagesGotFromUserLibrary addObject:result];
        }

    }
};

ALAssetsLibraryGroupsEnumerationResultsBlock
libraryGroupsEnumeration = ^(ALAssetsGrouP* group,BOOL* stop){
    [group setAssetsFilter:[ALAssetsFilter allPhotos]];

    if (group!=nil)
    {

        [group enumerateAssetsUsingBlock:groupEnumerAtion];
    }
    else
    {

        dispatch_async(dispatch_get_global_queue(0,0),^{
            GalleryCollectionViewController *otherController = [[GalleryCollectionViewController alloc] init];
            [otherController receiveImagesWithMutableArray:imagesGotFromUserLibrary];

        });
    }

};



al = [[ALAssetsLibrary alloc] init];
[al enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos
                       usingBlock:libraryGroupsEnumeration
                     failureBlock:^(NSError *error){
                         NSLog(@"ERROR: %@",error);
                     }];

这是在viewDidLoad然后：

+ (ALAssetsLibrary *)defaultAssetsLibrary {
static dispatch_once_t pred = 0;
static ALAssetsLibrary *library = nil;
dispatch_once(&pred,^{
    library = [[ALAssetsLibrary alloc] init];
});
return library;
}

这段代码是将数组发送到另一个控制器,将控制器设置为UICollectionView.问题是,我收到错误“无效尝试访问其拥有的ALAssetsLibrary的生命周期”,如果我尝试使用NSLog我的数组,结果就像“ALAsset – Type：UnkNown”,URL：(null)“.

我抬头看了互联网,找到了一个解决方案.我应该添加这行代码,但它不起作用.代码是：

+ (ALAssetsLibrary *)defaultAssetsLibrary {
static dispatch_once_t pred = 0;
static ALAssetsLibrary *library = nil;
dispatch_once(&pred,^{
    library = [[ALAssetsLibrary alloc] init];
});
return library;
}

任何人都可以帮助我@L_618_0@正确的图片网址来显示？