Set that code as a function in a service. Functions are for that.
To create a service see the link below.
How to inject $_SERVER variable into a Service
Note: don't forget to inject the mail service as an argument!
arguments: ["@mailer"]
After you set your service;
public function sendMail($data)
{
$msg = \Swift_Message::newInstance()
->setSubject($data['subject'])
->setFrom($data['from'])
->setTo($data['to'])
->setBody($this->renderView($data['view']));
$this->mailer->send($msg);
}
And you can call your service like;
// this code below is just for setting the data
$data = [
'subject' => 'Hello World!',
'from' => '[email protected]',
'to' => '[email protected]',
'template' => 'blabla.html.twig'
];
// this code below is the actual code that will save you
$mailer = $this->get('my_mailer_service');
$mailer->sendMail($data);