//根据时间戳获取周几
- (NSString *)getWeekFromDate:(NSDate *)date
{
    NSCalendar *gregorian = [[NSCalendar alloc]
                             initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
    NSDateComponents *weekdayComponents =
    [gregorian components:NSCalendarUnitWeekday fromDate:date];
    NSInteger _weekday = [weekdayComponents weekday];
    NSString *weekStr;
    if (_weekday == 1){
        weekStr = @"Sun";
    }else if (_weekday == 2) {
        weekStr = @"Mon";
    }else if (_weekday == 3){
        weekStr = @"Tue";
    }else if (_weekday == 4){
        weekStr = @"Wed";
    }else if (_weekday == 5){
        weekStr = @"Thu";
    }else if (_weekday == 6){
        weekStr = @"Fri";
    }else if (_weekday == 7){
        weekStr = @"Sat";
    }
    return weekStr;
}