iOS开发-对数组进行排序

<pre name="code" class="objc">-(NSMutableArray*)backDescendingOrderArray:(NSMutableArray *)array{    [array sortUsingComparator:^NSComparisonResult(id  _Nonnull obj1, id  _Nonnull obj2)    {        RecentlyNoticeModel *modela = (RecentlyNoticeModel *)obj1;        RecentlyNoticeModel *modelb = (RecentlyNoticeModel *)obj2;        int aNum = [modela.time floatValue];        int bNum = [modelb.time floatValue];        if (aNum < bNum) {            return NSOrderedDescending;        }        else if (aNum > bNum)        {            return NSOrderedAscending;        }        else        {            return NSOrderedSame;        }    }];   return array;}