iOS

• 在给定时间与当前时间进行对比,用途: 验证码是否过期?

• 获取当前时间NSDate

#pragma mark -得到当前时间date
- (NSDate *)getCurrentTime{
    
    //2017-04-24 08:57:29
    NSDateFormatter *formatter=[[NSDateFormatter alloc]init];
    [formatter setDateFormat:@"yyyy-MM-dd hh:mm:ss"];
    NSString *dateTime=[formatter stringFromDate:[NSDate date]];
    NSDate *date = [formatter dateFromString:dateTime];
//    [formatter setDateFormat:@"yyyy-MM-dd hh:mm:ss"];
//    NSString *dateString = [formatter stringFromDate:date];
//    NSLog(@"datastring  = %@",dateString);
    return date;
}

• 将服务器返回的时间字符串转换为date格式

    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"yyyy-MM-dd hh:mm:ss"];
//下面以 '2017-04-24 08:57:29'为例代表服务器返回的时间字符串
    NSDate *date = [dateFormatter dateFromString:@"2017-04-24 08:57:29"];

• 时间对比:
• 返回1 - 过期, 0 - 相等, -1 - 没过期

- (int)compareOneDay:(NSDate *)oneDay withAnotherDay:(NSDate *)anotherDay
{
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"yyyy-MM-dd hh:mm:ss"];
    NSString *oneDayStr = [dateFormatter stringFromDate:oneDay];
    NSString *anotherDayStr = [dateFormatter stringFromDate:anotherDay];
    NSDate *dateA = [dateFormatter dateFromString:oneDayStr];
    NSDate *dateB = [dateFormatter dateFromString:anotherDayStr];
    NSComparisonResult result = [dateA compare:dateB];
    NSLog(@"oneDay : %@, anotherDay : %@", oneDay, anotherDay);
    if (result == NSOrderedDescending) {
        //在指定时间前面 过了指定时间 过期
        NSLog(@"oneDay  is in the future");
        return 1;
    }
    else if (result == NSOrderedAscending){
        //没过指定时间 没过期
        //NSLog(@"Date1 is in the past");
        return -1;
    }
    //刚好时间一样.
    //NSLog(@"Both dates are the same");
    return 0;
    
}

常用语验证码过期.封装到公共类最好.

• 以下转自 http://www.cnblogs.com/zhang-kiwi/p/5009019.html

/*=============================NSDate日期类的使用=============================*/
    
    // 获取当前时间，获得的时0市区的时间跟北京时间相差8小时
    NSDate *currentDate = [NSDate date]; // GMT
    NSLog(@"currentDate :%@",currentDate);
    
    //timeIntervalSince1970 到1970-1-1的秒数，也叫时间戳（NSTimeInterval）
    NSTimeInterval interval1970 = [currentDate timeIntervalSince1970];
    NSLog(@"interval = %lf",interval1970);
    
    // timeIntervalSinceReferenceDate 到2001-1-1 的秒数
    NSTimeInterval interval2001 = [currentDate timeIntervalSinceReferenceDate];
    NSLog(@"interval2001 = %lf",interval2001);
    
    // timeIntervalSinceNow 距当前时间的秒数
    NSTimeInterval intervalNow = [currentDate timeIntervalSinceNow];
    NSLog(@"intervalNow = %lf",intervalNow);
    
    
    
    NSTimeInterval hour = 60 * 60;
    // 一小时后
    NSDate *h1 = [currentDate dateByAddingTimeInterval:hour];
    NSLog(@"h1 :%@",h1);
    
    // 一小时前
    NSDate *h2 = [currentDate dateByAddingTimeInterval:-hour];
    NSLog(@"h2 :%@",h2);
    
    // 计算北京时区时间，（使用系统当前的时区：systemTimeZone）
    NSTimeInterval inter = [[NSTimeZone systemTimeZone] secondsFromGMT];
    NSDate *bjDate = [currentDate dateByAddingTimeInterval:inter];
    NSLog(@"bjDate :%@",bjDate);
    
    
    
    NSTimeInterval day = 24 * 60 * 60;
    // 方式一：
    //        NSDate *yesterday = [NSDate dateWithTimeIntervalSinceNow:-day];
    // 方式二：
    
    // 昨天
    NSDate *yesterday = [bjDate dateByAddingTimeInterval:-day];
    NSLog(@"yesterday:%@",yesterday);
    
    // 今天
    NSDate *today = [bjDate dateByAddingTimeInterval:0];
    NSLog(@"today:%@",today);
    
    // 明天
    NSDate *tomorrow = [bjDate dateByAddingTimeInterval:day];
    NSLog(@"tomorrow:%@",tomorrow);
    
    // isEqualToDate 两个日期的比较
    if ([yesterday isEqualToDate:tomorrow]) {
        
        NSLog(@"两个日期相同");
        
    } else {
        
        NSLog(@"两个日期不相同");
        
    }
    
    // compare 两个日期的比较
    NSComparisonResult result = [yesterday compare:tomorrow];
    if (result == NSOrderedAscending) {
        
        NSLog(@"日期升序");
        
    } else if(result == NSOrderedSame) {
        
        NSLog(@"两个日期相同");
        
    } else if(result == NSOrderedDescending) {
        
        NSLog(@"两个日期降序");
    }
    
    //distantFuture 未来的一个时间 4001-01-01 00:00:00
    NSDate *future = [NSDate distantFuture];
    NSLog(@"future :%@",future);
    //distantPast 远古的一个时间 0001-12-30 00:00:00
    NSDate *past = [NSDate distantPast];
    NSLog(@"past :%@",past);
    
    
    // dateWithTimeIntervalSince1970 将时间戳转为日期类型
    NSString *time = @"34567898";
    NSDate *timeDate = [NSDate dateWithTimeIntervalSince1970:[time doubleValue]];
    NSLog(@"timeDate :%@",timeDate);
    
    NSDate *now = [NSDate date];
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"yyyy年MM月dd日 HH:mm:ss"];
    
    // 2014年10月15日 16:35:42
    // stringFromDate 将日期类型格式化，转为NSString 类型
    NSString *current = [formatter stringFromDate:now];
    NSLog(@"current:%@",current);
    
    //dateFromString 将时间字符串转化为日期类型，
    [formatter setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]]; // 默认使用0时区，所以需要时区的转换
    NSDate *nowDate = [formatter dateFromString:current];
    NSLog(@"nowDate :%@",nowDate);

• 获取时间戳

-(NSString*)getCurrentTimestamp{
    NSDate* dat = [NSDate dateWithTimeIntervalSinceNow:0];
    NSTimeInterval a=[dat timeIntervalSince1970];
    NSString*timeString = [NSString stringWithFormat:@"%0.f", a];//转为字符型
    return timeString;
}