if anyone has this problem too...
i have the solution:
return $this->view->getRender('emails', $name, $params, function($view) {
$view->setRenderLevel(View::LEVEL_LAYOUT);
});
where emails is the folders that contain templates,
$name is the name of the template for attach
and any $params to pass to the template
in this case i use this function to pass the view how template for email (swiftmailer)
$mailer->subject(_('Ha ocurrido un error en el sistema'))
->to($support_email_contacts)
->message($mailer->template('senderror', array(
'siteName' => $this->config->client->siteName
))
)->from(array($contact_email => $contact_company))->send(FALSE);
;)