Symfony\Component\Serializer\SerializerInterface::serialize PHP Метод

    function serialize($data, $format);

 /**
  * In an API context, converts any data to a XML response.
  *
  * @param GetResponseForControllerResultEvent $event
  *
  * @return Response|mixed
  */
 public function onKernelView(GetResponseForControllerResultEvent $event)
 {
     $controllerResult = $event->getControllerResult();
     if ($controllerResult instanceof Response) {
         return $controllerResult;
     }
     $request = $event->getRequest();
     $format = $request->attributes->get('_api_format');
     if (self::FORMAT !== $format) {
         return $controllerResult;
     }
     switch ($request->getMethod()) {
         case Request::METHOD_POST:
             $status = 201;
             break;
         case Request::METHOD_DELETE:
             $status = 204;
             break;
         default:
             $status = 200;
             break;
     }
     $resourceType = $request->attributes->get('_resource_type');
     $response = new Response($this->serializer->serialize($controllerResult, self::FORMAT, $resourceType->getNormalizationContext()), $status, ['Content-Type' => 'application/xml']);
     $event->setResponse($response);
 }