autoload helper file codeigniter 4

<?php
// BaseController.php
namespace App\Controllers;
use CodeIgniter\Controller;
class BaseController extends Controller {
  protected $helpers = ['common'];
  public function initController(\CodeIgniter\HTTP\RequestInterface $request, \CodeIgniter\HTTP\ResponseInterface $response, \Psr\Log\LoggerInterface $logger) {
    parent::initController($request, $response, $logger);
  }
}

<?php
BaseController.php
function public_url($url = '') {
  return base_url('public/' . $url);
}

<?php  
	// layout.php
	echo '<pre>';
		echo public_url('abc');
	echo '</pre>';
?>