CodeIgniter 3 MY_Controller

MY_Controller.php

<?php

class MY_Controller extends CI_Controller
{

  protected $data = array();

  function __construct()
  {
    parent::__construct();
    $this->data['pagetitle'] = 'My First CMS';
  }

  protected function render($the_view = NULL, $template = 'backend')
  {
      if($template == 'json' || $this->input->is_ajax_request())
      {
          header('Content-Type: application/json');
          echo json_encode($this->data);
      }
      elseif(is_null($template))
      {
          $this->load->view($the_view,$this->data);
      }
      else
      {
          $this->data['content'] = (is_null($the_view)) ? '' : $this->load->view($the_view,$this->data, TRUE);
          $this->load->view('templates/'.$template.'/index', $this->data);
      }
  }

}

class Admin_Controller extends MY_Controller
{
  function __construct()
  {
    parent::__construct();
  }
}

class Public_Controller extends MY_Controller
{
  function __construct()
  {
    parent::__construct();
  }
}