public function load($xmlString)
    {
        $data   =  $this->parserXml($xmlString);

        if (!isset($data['MsgType'])) {
            throw new \RuntimeException("can not found MsgType");
        }

        // event message
        if (WxReceive::MSG_TYPE_EVENT == $data['MsgType']) {
            $parser = new Event\Parser();
            return $parser->load($data);
        }

        // other message
        $parser = new Message\Parser();
        return $parser->load($data);
    }