for::matchUAAgainstKey

protected function matchUAAgainstKey($key)
    {
        // Make the keys lowercase so we can match: isIphone(), isiPhone(), isiphone(), etc.
	$key = mb_strtolower($key);
        if (false === isset($this->cache[$key])) {

            // change the keys to lower case
            $_rules = array_change_key_case($this->getRules());

            if (false === empty($_rules[$key])) {
                $this->cache[$key] = $this->match($_rules[$key]);
            }

            if (false === isset($this->cache[$key])) {
                $this->cache[$key] = false;
            }
        }

        return $this->cache[$key];
    }