gistfile1.m

+ (NSString *)sinceStringForDate:(NSDate *)date longFormat:(BOOL)longFormat
{
    NSTimeInterval sinceNow = -[date timeIntervalSinceNow];
    NSString *num = @"";
    NSString *units = @"";
    
    const NSTimeInterval ONE_MIN = 60;
    const NSTimeInterval ONE_HOUR = ONE_MIN * 60;
    const NSTimeInterval ONE_DAY = ONE_HOUR * 24;
    
    if (roundf(sinceNow) <= 0.0f)
    {
        num = @"now";
    }
    else if (sinceNow < ONE_MIN)
    {
        num = [NSString stringWithFormat:@"%2.f", floorf(sinceNow)];
        units = longFormat ? @" seconds ago" : @"s";
    }
    else if (sinceNow < ONE_HOUR)
    {
        num = [NSString stringWithFormat:@"%2.f", floorf(sinceNow / ONE_MIN)];
        units = longFormat ? @" minutes ago" : @"m";
    }
    else if (sinceNow > ONE_HOUR && sinceNow < ONE_HOUR * 2)
    {
        num = [NSString stringWithFormat:@"%2.f", floorf(sinceNow / ONE_HOUR)];
        units = longFormat ? @" hour ago" : @"h";
    }
    else if (sinceNow < ONE_DAY)
    {
        num = [NSString stringWithFormat:@"%2.f", floorf(sinceNow / ONE_HOUR)];
        units = longFormat ? @" hours ago" : @"h";
    }
    else
    {
        num = [NSString stringWithFormat:@"%2.f", floorf(sinceNow / ONE_DAY)];
        units = longFormat ? @" days ago" : @"d";
    }
    
    return [NSString stringWithFormat:@"%@%@", num, units];
}