Render template and return response at the same time in Symfony

I want to generate a PDF file and send it in an email as an attachment using Swift Mailer and knp-snappy-bundle. The problem is it generates and downloads the PDF file only without rendering the template. I want it to generate the PDF and render the template at the same time.

Code:

public function viewPostAction() {
  $html = "Just a sample text to produce the PDF";

  return new Response(
    $this->get('knp_snappy.pdf')->getOutputFromHtml($html),
    200,
    array(
      'Content-Type'          => 'application/pdf',
      'Content-Disposition'   => 'attachment; filename="classement.pdf"'
    )
  );
  $message = \Swift_Message::newInstance()
    ->setSubject('Some Subject')
    ->setFrom('test@gmail.com')
    ->setTo('test@gmail.com')
    ->setBody("test email")
    ->attach(Swift_Attachment::fromPath('C:\Users\acer\Downloads\classement.pdf'));

  # Send the message
  $this->get('mailer')
    ->send($message);
  $post = $this->getDoctrine()->getRepository('AppBundle:Post')->findAll();
  return $this->render("pages/index.html.twig", ['post' => $post]);
}

Your code returns the PDF that it creates, that's why the rest is not executed. You should change

return new Response(
    $this->get('knp_snappy.pdf')->getOutputFromHtml($html),
    200,
    array(
        'Content-Type'          => 'application/pdf',
        'Content-Disposition'   => 'attachment; filename="classement.pdf"'
    )
);

into the code that generates local PDF file:

$this->get('knp_snappy.pdf')->generateFromHtml($html, 'C:\Users\acer\Downloads\classement.pdf');