数据存储、排序

在项目遇到这么一个场景，从SQL数据库取出数据，按声母排序，耗时间比较长，固做了以下优化：
开始直接在viewDidLoad调用

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
        _dataRecentContact =  [FeedUserListHelper getUserListContactDataBy:[FeedRecentContactListSQL lookFeedRecentContactList]];
        //关注列表
        _dataFocus = [KLFeedNoteNameSQL lookFeedMerchantFocusList];
        _dataHotUserArray = [FeedHotUserListSQL lookFeedHotUserList];
        _rowArray = [FeedUserListHelper getUserListDataBy:_dataFocus];
        _letterArray  = [FeedUserListHelper getUserListSectionBy:[_rowArray mutableCopy]];
    });

但是需要@的入口太多，到处都需要设置属性，后来觉得应该写在单例好了,放在UITabBarController调用

func getDataForFeedAltetUserList() {
        dataRecentContact = FeedUserListHelper.getUserListContactDataBy(FeedRecentContactListSQL.lookFeedRecentContactList()) as NSMutableArray
        dataFocus = KLFeedNoteNameSQL.lookFeedMerchantFocusList()
        dataHotUserArray = FeedHotUserListSQL.lookFeedHotUserList()
        rowArray = FeedUserListHelper.getUserListDataBy(getDataFocus())
        letterArray = FeedUserListHelper.getUserListSectionBy(getRowArray().mutableCopy() as! NSMutableArray)
    }