Using Twig functions inside of Slim
Twig and Slim are a great combination to work with, with Twig's advanced templating parser it allows flexibility when working on projects using it. I have seen questions being asked a few times about how to access Twig related functions inside of Slim.
Twig view class (TwigView or Slim\Extras\Views\Twig) provided in the Slim Extras repository allows us to use Twig as a View for any Slim project. We have kept a copy of the Twig instance inside of the Twig view class (TwigView or Slim\Extras\Views\Twig) to allow you to access Twig easily from inside of Slim. The code below
$twig = $app->view()->getEnvironment();
You now have access to the Twig environment, with this you can call Twig related functions.
$twig->addGlobal('siteName', 'Slim Awesomeness!');
Hope this has been helpful to you.