@implementation NSDate (whenString)

- (NSDate *)dateWithZeroTime
{
NSCalendar *calendar = [NSCalendar currentCalendar];
unsigned unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSWeekdayCalendarUnit;
NSDateComponents *comps = [calendar components:unitFlags fromDate:self];
[comps setHour:0];
[comps setMinute:0];
[comps setSecond:0];
return [calendar dateFromComponents:comps];
}

- (NSString *)whenString
{
NSDate *selfZero = [self dateWithZeroTime];
NSDate *todayZero = [[NSDate date] dateWithZeroTime];
NSTimeInterval interval = [todayZero timeIntervalSinceDate:selfZero];
int dayDiff = interval/(60*60*24);

// Initialize the formatter.
NSDateFormatter *formatter = [[[NSDateFormatter alloc] init] autorelease];

if (dayDiff == 0) { // today: show time only
[formatter setDateStyle:NSDateFormatterNoStyle];
[formatter setTimeStyle:NSDateFormatterShortStyle];
} else if (dayDiff == 1 || dayDiff == -1) {
//return NSLocalizedString((dayDiff == 1 ? @”Yesterday” : @”Tomorrow”), nil);
[formatter setDoesRelativeDateFormatting:YES];
[formatter setDateStyle:NSDateFormatterMediumStyle];
[formatter setTimeStyle:NSDateFormatterNoStyle];
} else if (dayDiff <= 7) { // < 1 week ago: show weekday
[formatter setDateFormat:@"EEEE"];
} else { // show date
[formatter setDateStyle:NSDateFormatterShortStyle];
[formatter setTimeStyle:NSDateFormatterNoStyle];
}

return [formatter stringFromDate:self];
}

@end