Call PHP function from Twig template
Its not possible to access any PHP function inside Twig directly.
What you can do is write a Twig extension. A common structure is, writing a service with some utility functions, write a Twig extension as bridge to access the service from twig. The Twig extension will use the service and your controller can use the service too.
Take a look: http://symfony.com/doc/current/cookbook/templating/twig_extension.html
Cheers.
There is already a Twig extension that lets you call PHP functions form your Twig templates like:
Hi, I am unique: {{ uniqid() }}.
And {{ floor(7.7) }} is floor of 7.7.
See official extension repository.