IOS 获取N天 前后的日期

//设置日期最大及最小值

datePicker.maximumDate = [self getTimeAfterNowWithDay:5];//5天后日期
datePicker.minimumDate = [self getTimeAfterNowWithDay:-5];//5天前日期

/**
 得到当前时间N天前后的日期
 @param day   传入正数 n天后   传入负数 N天前
 @return return value description
 */
- (NSDate *)getTimeAfterNowWithDay:(int)day
{
    NSDate *nowDate = [NSDate date];
    NSDate *theDate;
    
    if(day!=0)
    {
        NSTimeInterval  oneDay = 24*60*60*1;  //1天的长度
        theDate = [nowDate initWithTimeIntervalSinceNow: oneDay*day ];

    }
    else
    {
        theDate = nowDate;
    }
    return theDate;
}