Symfony\Component\HttpFoundation\Response::setVary PHP Method

    public function setVary($headers, $replace = true)
    {
        $this->headers->set('Vary', $headers, $replace);

        return $this;
    }

 public function indexAction(Request $request)
 {
     //mini formulaire d'abonnement
     $news = new Newsletter();
     $form = $this->createFormBuilder($news)->add('news', 'email')->add('Envoyer', 'submit')->getForm();
     $form->handleRequest($request);
     if ($form->isValid()) {
         $email = $news->getNews();
         $message = \Swift_Message::newInstance()->setSubject('Bonjour')->setFrom($email)->setTo('*****@*****.**')->setBody('Bonjour Fabrice cet email : ' . $email . ' souhaite un abonnement à votre newsletter, cordialement');
         $this->get('mailer')->send($message);
         return $this->redirect($this->generateUrl('front_homepage'));
     }
     $essais = $this->getCat('essais');
     $arr = $this->get('front.base.service')->recupInfo();
     $arr['essais'] = $essais;
     $arr['nav_accueil'] = ' ';
     $arr['nav_xix'] = ' ';
     $arr['nav_essais'] = 'active';
     $arr['nav_litt'] = ' ';
     $arr['nav_audio'] = ' ';
     $arr['nav_video'] = ' ';
     $arr['nav_info'] = ' ';
     $arr['newsletter'] = $form->createView();
     $response = new Response();
     if ($this->getRequest()->isMethod('GET')) {
         $response->setPublic();
         $response->setSharedMaxAge(1);
         $response->setVary(array('Accept-Encoding', 'User-Agent'));
     }
     return $this->render('FrontBundle:Essais:index.html.twig', $arr, $response);
 }