AssetsLibrary/AssetsLibrary.h 相册获取

ios8.0以前获取相册有UIImagePicker（但是每次只能选取一张），如果需要选取多张，只能自己来自定义picker

这里用到的框架为AssetsLibrary.framework,资源库，

#import <AssetsLibrary/ALAsset.h> //图片的基本信息

#import <AssetsLibrary/ALAssetsFilter.h> //Group的过滤器，记住，只能生效一个

#import <AssetsLibrary/ALAssetsGroup.h>//获取相册

#import <AssetsLibrary/ALAssetsLibrary.h>//额 整个类库的管理类吧

#import <AssetsLibrary/ALAssetRepresentation.h> //图片的详细信息

我这边简单的封装了一下，大致的流程就是先获取相册，然后再获取相册中的照片，比较简单，直接上代码吧

- (NSMutableDictionary *)detailGroups {

    if (!_detailGroups) {
        _detailGroups = @{}.mutableCopy;
    }

    return _detailGroups;
}

- (ALAssetsLibrary *)library {
    if (!_library) {
        _library = [[ALAssetsLibrary alloc]init];
    }
    return _library;
}

- (NSMutableArray *)assesGroups {

    if (!_assesGroups) {
        _assesGroups = @[].mutableCopy;
    }

    return _assesGroups;
}

+ (LIUAsset *)shareAsset {

    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _shareAsset = [[LIUAsset alloc]init];
    });

    return _shareAsset;
}

- (void)releaseObj {
    if (_shareAsset) {
        _shareAsset = nil;
    }
}

///获取所有的分组
- (void)getAssetsGroups:(GetAssetsGroupsBlock)assetsGroup {

    if (self.assesGroups.count != 0) {
        if (assetsGroup) {
            assetsGroup(self.assesGroups.copy);
            return;
        };
    }

    [self.library enumerateGroupsWithTypes:ALAssetsGroupAll usingBlock:^(ALAssetsGroup *group, BOOL *stop) {

        //只需要photo
        ALAssetsFilter *onlyPhotos = [ALAssetsFilter allPhotos];
        if (group) {

            [group setAssetsFilter:onlyPhotos];
            if ([group numberOfAssets] > 0) {
                [self.assesGroups addObject:group];
            }

        }else {
            //这里本来应该是要按照*stop来判断的，貌似调试的时候发现这个stop一直是no，但是有一个参考的是这里的group当是最后一个的时候 会是nil，就根据这个判断吧
            if (assetsGroup) {
                assetsGroup(self.assesGroups.copy);
                return;
            }
        }

    } failureBlock:^(NSError *error) {

    }];

}

///获取分组所有的alasset
- (void)getAllAssetsByGroup:(ALAssetsGroup *)group Finish:(GetAssetsBlock)finish{

    NSString *groupName = [group valueForProperty:ALAssetsGroupPropertyName];
    __block NSMutableArray *allAssets = [self.detailGroups objectForKey:groupName];

    if (allAssets) {
        //返回数据了
        if (finish) {
            finish(allAssets.copy);
        }
        return;
    }
    //如果没有数据
    allAssets = @[].mutableCopy;

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

        //不知道为什么这里的stop显示不对呀
        if (result) {
            [allAssets addObject:result];
        }else {
            //先把数组保存到字典中
            [self.detailGroups setObject:allAssets forKey:groupName];
            if (finish) {
                finish(allAssets.copy);
            }
            return;
        }

    }];

}

///获取全屏图
- (UIImage *)getFullImageWitAsset:(ALAsset *)asset {
    return [UIImage imageWithCGImage:[[asset defaultRepresentation] fullScreenImage]];
}

///获取缩略图
- (UIImage *)getThumbImageWithAsset:(ALAsset *)asset {
    return [UIImage imageWithCGImage:[asset thumbnail]];
}

ios 8以后，苹果就舍弃了这个类库，新建了一个photos类，下次有空再整理一下这个类库的