我使用这个方法将unix时间戳更改为一个可读的相对字符串。可能在新的一年的前几天没有正常工作，但希望你太过于注意。

I made this method to change the unix time stamp into a nice readable, relative string. Probably doesn't work properly in the first few days of a new year, but hopefully you should be too hungover to notice.

-(NSString *)relativeTime:(int)datetimestamp
{
    NSDate *aDate = [NSDate dateWithTimeIntervalSince1970:datetimestamp];
    NSCalendar *calendar = [NSCalendar currentCalendar];
    unsigned int unitFlags =  NSYearCalendarUnit|NSMonthCalendarUnit|NSWeekCalendarUnit|NSWeekdayOrdinalCalendarUnit|NSWeekdayCalendarUnit|NSDayCalendarUnit|NSHourCalendarUnit|NSMinuteCalendarUnit;
    NSDateComponents *messageDateComponents = [calendar components:unitFlags fromDate:aDate];
    NSDateComponents *todayDateComponents = [calendar components:unitFlags fromDate:[NSDate date]];

    NSUInteger dayOfYearForMessage = [calendar ordinalityOfUnit:NSDayCalendarUnit inUnit:NSYearCalendarUnit forDate:aDate];
    NSUInteger dayOfYearForToday = [calendar ordinalityOfUnit:NSDayCalendarUnit inUnit:NSYearCalendarUnit forDate:[NSDate date]];


    NSString *dateString;

    if ([messageDateComponents year] == [todayDateComponents year] && 
        [messageDateComponents month] == [todayDateComponents month] &&
        [messageDateComponents day] == [todayDateComponents day]) 
    {
        dateString = [NSString stringWithFormat:@"%02d:%02d", [messageDateComponents hour], [messageDateComponents minute]];
    } else if ([messageDateComponents year] == [todayDateComponents year] && 
               dayOfYearForMessage == (dayOfYearForToday-1))
    {
        dateString = @"Yesterday";
    } else if ([messageDateComponents year] == [todayDateComponents year] &&
               dayOfYearForMessage > (dayOfYearForToday-6))
    {

        NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
        [dateFormatter setDateFormat:@"EEEE"];
        dateString = [dateFormatter stringFromDate:aDate];
        [dateFormatter release];

    } else {

        NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
        [dateFormatter setDateFormat:@"yy"];
        dateString = [NSString stringWithFormat:@"%02d/%02d/%@", [messageDateComponents day], [messageDateComponents month], [dateFormatter stringFromDate:aDate]];
        [dateFormatter release];
    }

    return dateString;
}