Getting base_url into a PHP file of symfony3 framework

I am beginner into the symfony framework and I want to get the base url of

symfony3 framework into the view file. I did R&D and get how to get the base url into twig file using this.

But my view

Not twig file it it is .php file

So I don't know how to use the base url in the view .php file.

I get the base url into the head.blade.PHP file of Laravel framework using:-

<?php echo URL::to('/'); ?>

I want to like this into symfony3 framework.

via Chebli Mohamed