ALAssetsGroup

ALAssetsGroup

 

http://blog.sina.com.cn/s/blog_6d9cecaf0101eyec.html

ALAssetsGroup类是系统用于映射相册资源中的每个相册，可以通过该类获取相册中的资源文件，并且能向相册中添加资源文件

    

    //保存图片到系统默认的相册中，使用cgimageref的形式，并且选择图片以什么旋转方向的形式保存，并返回照片的url地址

   

    UIImage* image = [UIImage imageNamed:@"test.png"];

    [_library writeImageToSavedPhotosAlbum:[image CGImage] orientation:ALAssetOrientationLeft completionBlock:^(NSURL *assetURL, NSError *error) {

        NSLog(@"save image:%@",assetURL);

        //通过ALAssetsLibrary迭代取出所有相册

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

            NSString* groupname = [group valueForProperty:ALAssetsGroupPropertyName];

            //如果相册的名称是test的时候，对其进行操作

            if ([groupname isEqualToString:@"test"]) {

                //设置相册组的筛选条件，ALAssetsFilter类表示筛选条件，allPhotos代表相册只包含相片，allVideos代表只包含视频，allAssets代表包含所有资源

                [group setAssetsFilter:[ALAssetsFilter allPhotos]];

                //通过刚保存的照片的url，把保存到默认相册的照片也保存到test相册中

                [_library assetForURL:assetURL resultBlock:^(ALAsset *asset) {

                    //添加资源到指定的相册

                    [group addAsset:asset];

                    //获取相册中一共的资源数量

                    int count = [group numberOfAssets];

                    NSLog(@"count:%d",count);

                    dispatch_queue_t main = dispatch_get_main_queue();

                    dispatch_async(main, ^{

                        //获取相册的封面图片

                        CGImageRef poster = [group posterImage];

                        [imageView setImage:[UIImage imageWithCGImage:poster]];

                    });

                    //NSString *const ALAssetsGroupPropertyName;

                    //NSString *const ALAssetsGroupPropertyType;

                    //NSString *const ALAssetsGroupPropertyPersistentID;

                    //NSString *const ALAssetsGroupPropertyURL;

                    //查看相册的名字

                    NSLog(@"ALAssetsGroupPropertyName:%@",[group valueForProperty:ALAssetsGroupPropertyName]);

                    //查看相册的类型

                    NSLog(@"ALAssetsGroupPropertyType:%@",[group valueForProperty:ALAssetsGroupPropertyType]);

                    //查看相册的存储id

                    NSLog(@"ALAssetsGroupPropertyPersistentID:%@",[group valueForProperty:ALAssetsGroupPropertyPersistentID]);

                    //查看相册存储的位置地址

                    NSLog(@"ALAssetsGroupPropertyURL:%@",[group valueForProperty:ALAssetsGroupPropertyURL]);

                    //按遍历顺序获取指定索引的资源，遍历顺序可以是先序或倒序

                   

                    [group enumerateAssetsAtIndexes:[NSIndexSet indexSetWithIndex:0] options:NSEnumerationConcurrent usingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) {

                        

                    }];

                    //按顺便遍历获取相册中所有的资源，index代表资源的索引，stop赋值为false时，会停止遍历

                    [group enumerateAssetsUsingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) {

                        

                    }];

                     //按顺便遍历获取相册中所有的资源，遍历顺序可以是先序或倒序，index代表资源的索引，stop赋值为false时，会停止遍历

                    [group enumerateAssetsWithOptions:NSEnumerationReverse usingBlock:^(ALAsset *result, NSUInteger index, BOOL *stop) {

                        

                    }];

                    

                } failureBlock:^(NSError *error) {

                    

                }];

            }

        } failureBlock:^(NSError *error) {

            

        }];

    }];