如何在渲染特定视图时插入布局伏特？

I'm struggling on lack of doc issue on view and controller details about Phalcon,

what I'm doing in index.php is like,

    $viewCollections = new MicroCollection() ;
    $viewCollections->setHandler('BackenduiController',true) ;
    $viewCollections->get('/main/index', 'index');
    $app->mount($viewCollections) ;

In my controller,

<?php
use Phalcon\Mvc\View;
class BackenduiController extends ControllerBase
{

    public function initialize()
    {

    }

    public function index()
    {

        $this->tag->setTitle('A | B');
        $this->view->setTemplateAfter('nav') ;

        $this->view->render(
                "main","index"
            );


    }


}

My view volt file structure is like,

views

--layouts
----index.volt
----nav.volt
--main
----index.volt
--index.volt

the nav.volt is just a nav bar piece of html code, my purpose is to insert the nav bar code in the main/index page, however if I use setTemplateAfter, the result page is only the nav piece of code, not showing the index page at all. So How should I arrange the code to make the controller rendering the correct page?

What I`m doing is to use the include.

Place this in the index.volt where the nav should be

{% include "layouts/nav.volt" %}

should do the trick