yii\web\Response::getStatusCode PHP Method

    public function getStatusCode()
    {
        return $this->_statusCode;
    }

 public function afterAction($action, $result)
 {
     $result = parent::afterAction($action, $result);
     if ($this->response->getStatusCode() == 200) {
         return $this->respondByFormat();
     }
     return $result;
 }