iOS时间合并

合并同一时间的课程，同一时间可能有多个课程，比如13:30-14:00 13:40-14:40

//递归实现
-(void)mergeClassSchedule:(NSMutableArray*)ary
                 retArray:(NSMutableArray*)retAry
                 beginDate:(NSDate*)beginDate
                 endDate:(NSDate*)endDate
{
    NSMutableArray *groupAry=[NSMutableArray new];
    if ([ary count]>0) {
        [retAry addObject:groupAry];
    }
    while ([ary count]>0)
    {
       
        XSClassScheduleModel *classSchedulemodel=[ary objectAtIndex:0];
        if (beginDate==nil)
        {
           beginDate=[XSUtil str2DateEx:classSchedulemodel.BeginDateTimeUTC];
           endDate=[XSUtil str2DateEx:classSchedulemodel.EndDateTimeUTC];
           
           [groupAry addObject:classSchedulemodel];
           
           [ary removeObjectAtIndex:0];
        }
        else
        {
            NSDate *beginDate2=[XSUtil str2DateEx:classSchedulemodel.BeginDateTimeUTC];
            NSDate *endDate2=[XSUtil str2DateEx:classSchedulemodel.EndDateTimeUTC];
           
            if (([beginDate compare:beginDate2]==NSOrderedAscending || [beginDate compare:beginDate2]==NSOrderedSame)
                && [endDate compare:beginDate2]==NSOrderedDescending)
            {
                [groupAry addObject:classSchedulemodel];
                [ary removeObjectAtIndex:0];
                 endDate=[endDate compare:endDate2]==NSOrderedAscending?endDate2:endDate;
            }
            else
            {

                beginDate=nil;
                [self mergeClassSchedule:ary retArray:retAry beginDate:beginDate endDate:endDate];
  
            }

        }
    }
}