code: public function getApp()
      {
          if (!self::$_app instanceof Factory)
          {
              self::$_app = Factory::officialAccount(Yii::$app->params['wechatConfig']);
          }
  
          return self::$_app;
      }
docs: 获取 EasyWeChat 微信实例
  
  @return Factory|\EasyWeChat\OfficialAccount\Application