显示一天，一小时前不能正常工作？

Question

我已完成此代码

+ (NSString *)relativeDateStringForDate:(NSString *)date
{
    NSString *temp;

    NSString* format = @"yyyy-MM-dd'T'HH:mm:ss.SSS'Z'";
    // Set up an NSDateFormatter for UTC time zone
    NSDateFormatter* formatterUtc = [[NSDateFormatter alloc] init];
    [formatterUtc setDateFormat:format];
    [formatterUtc setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
    // Cast the input string to NSDate
    NSDate* utcDate = [formatterUtc dateFromString:date];
    // Set up an NSDateFormatter for the device's local time zone
    NSDateFormatter* formatterLocal = [[NSDateFormatter alloc] init];
    [formatterLocal setDateFormat:format];
    [formatterLocal setTimeZone:[NSTimeZone localTimeZone]];
    // Create local NSDate with time zone difference
    NSDate* localDate = [formatterUtc dateFromString:[formatterLocal stringFromDate:utcDate]];
    //calender settings
    NSCalendarUnit units = NSDayCalendarUnit | NSWeekOfYearCalendarUnit |
    NSMonthCalendarUnit | NSYearCalendarUnit | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond ;
    NSCalendar *cal = [NSCalendar currentCalendar];

    //local dates
    NSDate* datetime = [NSDate date];
    NSDateFormatter* dateFormatter = [[NSDateFormatter alloc] init];
    [formatterUtc setTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:0]];
    [dateFormatter setDateFormat:format];
    NSString* dateTimeInIsoFormatForZuluTimeZone = [dateFormatter stringFromDate:datetime];
    NSDate* sysUTCDate = [dateFormatter dateFromString:dateTimeInIsoFormatForZuluTimeZone];


    NSDateFormatter* formatterLocalFromUtc = [[NSDateFormatter alloc] init];
    [formatterLocalFromUtc setDateFormat:format];
    [formatterLocalFromUtc setTimeZone:[NSTimeZone localTimeZone]];
    // Create local NSDate with time zone difference
    NSDate* curreentDate = [formatterUtc dateFromString:[formatterLocalFromUtc stringFromDate:sysUTCDate]];

    NSDateComponents *components1 = [cal components:(NSCalendarUnitEra|NSCalendarUnitYear|NSCalendarUnitMonth|NSCalendarUnitDay |NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond) fromDate:curreentDate];
    NSDate *today = [cal dateFromComponents:components1];

    //server date
    components1 = [cal components:(NSCalendarUnitEra|NSCalendarUnitYear|NSCalendarUnitMonth|NSCalendarUnitDay | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond) fromDate:localDate];
    NSDate *thatdate = [cal dateFromComponents:components1];



    // if `date` is before "now" (i.e. in the past) then the components will be positive
    NSDateComponents *components = [[NSCalendar currentCalendar] components:units
                                                                   fromDate:thatdate
                                                                     toDate:today
                                                                    options:0];



    if (components.year > 0) {
        temp=[NSString stringWithFormat:@"%ld years ago", (long)components.year];
    } else if (components.month > 0) {
        temp= [NSString stringWithFormat:@"%ld months ago", (long)components.month];
    } else if (components.weekOfYear > 0) {
        temp= [NSString stringWithFormat:@"%ld weeks ago", (long)components.weekOfYear];
    } else if (components.day > 0) {
        if (components.day > 1) {
            temp= [NSString stringWithFormat:@"%ld day ago", (long)components.day];
        } else {
            temp=[NSString stringWithFormat:@"%ld day ago", (long)components.day];
        }
    } else {
        if (components.hour!=0) {
            if(components.hour==1)
            {
                temp= [NSString stringWithFormat:@"%ld hour ago",(long)components.hour];
            }
            else
            {
                temp= [NSString stringWithFormat:@"%ld hours ago",(long)components.hour];
            }

        } else if (components.minute!=0){
            if(components.minute==1)
            {
                temp= [NSString stringWithFormat:@"%ld min ago",(long)components.minute];
            }
            else
            {
                temp=[NSString stringWithFormat:@"%ld mins ago",(long)components.minute];
            }

        }
        else if (components.second!=0){
            if(components.second==1)
            {
                temp= [NSString stringWithFormat:@"%ld sec ago",(long)components.second];
            }
            else
            {
                temp=[NSString stringWithFormat:@"%ld secs ago",(long)components.second];
            }

        }
    }
    return temp;
}

但它没有正确显示。如果我将任何记录发布到服务器，其显示 -1秒前 如何用上面的代码解决这个问题。

我的服务器日期响应为 NSString

2015-09-16T14：16：49.187Z

我需要用服务器日期差异来计算时间。

为了避免这种情况，我已经手动增加了+2秒

temp=[NSString stringWithFormat:@"%ld secs ago",(long)components.second+2]; 

这不是完成这项工作的好方法，请帮助我。