Dateから相対日時を返す

gistfile1.m

+ (NSString *)relativeDateStringFromDate:(NSDate *)date
{
    NSInteger sec = (int)[[NSDate date] timeIntervalSinceDate:date];
    
    if (sec < 60) {
        return @"たった今";
    }
    else if (sec < 120) {
        return @"1分前";
    }
    else if (sec < 3600) {
        return [NSString stringWithFormat:@"%d分前", sec / 60];
    }
    else if (sec < 7200) {
        return @"1時間前";
    }
    else if (sec < 86400) {
        return [NSString stringWithFormat:@"%d時間前", sec / 3600];
    }
    else if (sec < 172800) {
        return @"1日前";
    }
    else {
        return [NSString stringWithFormat:@"%d日前", sec / 86400];
    }
}