How to extract elapsed time from NSDate

dateSince.m

// - since {{{
- (NSString *)since
{
    // seed the test data. (in future passed in via a class instance variable)
    NSString *dateStr = @"Mon May 05 17:26:30 +0000 2008";

    // create our fommating object
    NSDateFormatter *dateFormat = [[[NSDateFormatter alloc] init] autorelease];
    [dateFormat setDateFormat:@"EEE MMM dd HH:mm:ss Z yyyy"];

    // create a date from the above string.
    NSDate *date = [dateFormat dateFromString:dateStr];

    // seconds between date and now. (cast to int)
    int timeSinceNow = (int) [date timeIntervalSinceNow];

    // convert negative to positive.
    if (timeSinceNow < 0)
    {
        timeSinceNow = timeSinceNow * -1;
    }

    // is interval less then a minute? print seconds.
    if (timeSinceNow < 60)
    {
        NSString *plural = (timeSinceNow > 1) ? @"s" : @"";

        return [NSString stringWithFormat:@"%d second%@ ago",
               round( timeSinceNow ), plural];
    }
    // is interval less then an hour? print minutes.
    else if (timeSinceNow < 60 * 60)
    {
        int minutes = round( timeSinceNow / 60 );
        NSString *plural = (minutes > 1) ? @"s" : @"";

        return [NSString stringWithFormat:@"%d minute%@ ago", minutes, plural];
    }
    // is interval less then a day? print hours and minutes.
    else if (timeSinceNow < 60 * 60 * 24)
    {
        int hours = round( timeSinceNow / (60 * 60) );
        NSString *pluralHours = (hours > 1) ? @"s" : @"";

        int minutes = round( ( timeSinceNow - (60 * 60) ) / 60 );
        NSString *pluralMinutes = (minutes > 1) ? @"s" : @"";

        return [NSString stringWithFormat:@"%d hour%@ and %d minute%@ ago",
               hours, pluralHours, minutes, pluralMinutes];
    }
    // more then a day? print formatted date.
    else
    {
        [dateFormat setDateStyle:NSDateFormatterShortStyle];
        [dateFormat setTimeStyle:NSDateFormatterShortStyle];

        return [dateFormat stringFromDate:date];
    }

} //}}}