IOS 根据日期，获取该日期所在周，月，年的开始日期，结束日期 的方法

- (void)getMonthBeginAndEndWith:(NSDate *)newDate{

    if (newDate == nil) {

        newDate = [NSDate date];

    }

    double interval = 0;

    NSDate *beginDate = nil;

    NSDate *endDate = nil;

    

    NSCalendar *calendar = [NSCalendar currentCalendar];

    [calendar setFirstWeekday:2];//设定周一为周首日

    BOOL ok = [calendar rangeOfUnit:NSMonthCalendarUnit startDate:&beginDate interval:&interval forDate:newDate];

//分别修改为 NSDayCalendarUnit NSWeekCalendarUnit NSYearCalendarUnit 

    if (ok) {

        endDate = [beginDate dateByAddingTimeInterval:interval-1];

    }else {

        return;

    }

    NSDateFormatter *myDateFormatter = [[NSDateFormatter alloc] init];

    [myDateFormatter setDateFormat:@"yyyy.MM.dd"];

    NSString *beginString = [myDateFormatter stringFromDate:beginDate];

    NSString *endString = [myDateFormatter stringFromDate:endDate];

    

    chooseDate.text = [NSString stringWithFormat:@"%@-%@",beginString,endString];

    [myDateFormatter release];

}