See: https://github.com/philipsharp/slim-view-plates for an installable package. Custom Slim Framework (http://www.slimframework.com/) view for Plates template system (http://platesphp.com/). License: MIT

index.php

<?php

$view = new \My\Views\Plates();
$view->fileExtension = 'phtml';

$app = new \Slim\Slim(array(
    'view'           => $view,
    'templates.path' => '../templates'
));

My\Views\Plates.php

<?php

namespace My\Views;

class Plates extends \Slim\View
{
    /**
     * @var \League\Plates\Engine
     */
    protected $_engineInstance;
    
    /**
     * Override for the default file extension
     *
     * @var string
     */
    public $fileExtension;
    
    public function getInstance()
    {
        if (!$this->_engineInstance) {
            // Create new Plates engine
            $this->_engineInstance = new \League\Plates\Engine($this->getTemplatesDirectory());
            
            if ($this->fileExtension){
                $this->_engineInstance->setFileExtension($this->fileExtension);
            }
        }

        return $this->_engineInstance;
    }
    
    public function render($template){
        $platesTemplate = new \League\Plates\Template($this->getInstance());
        $platesTemplate->data($this->all());
        return $platesTemplate->render($template);
    }
}