Integrate Codeigniter 4.0.2 vs Smarty 3.1.34

Hey guys
I'm gonna start my project with CodeIgniter and i need your help to integrate CodeIgniter 4.0.2 vs Smarty 3.1.34
I appreciate your help...

i fount this tutorial, but it's cofusing 
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Well, this is what I have done to use Smarty according to tutorials.

Downloaded the Smarty to app/ThirdParty/Smarty and created following folders: writable/smarty/templates_c and writable/smarty/cache

app/Libraries/CI4Smarty.php:

Code:

namespace App\Libraries;

require_once APPPATH.'ThirdParty/Smarty/Autoloader.php';

use \Smarty_Autoloader;

Smarty_Autoloader::register();

use \Smarty;

class CI4Smarty extends Smarty {

    public function __construct()
    {
        parent::__construct();
       
        parent::setTemplateDir(APPPATH . 'Views/');
        parent::setCompileDir(WRITEPATH . 'smarty/templates_c/')->setCacheDir(WRITEPATH . 'smarty/cache/');
       
    }

    public function view($tpl_name) {
        if (substr($tpl_name, -4) != '.tpl'){
            $tpl_name.='.tpl';
        }

        parent::display($tpl_name);
    }
}

app/Config/Services.php:

Code:

namespace Config;

use CodeIgniter\Config\Services as CoreServices;
use CodeIgniter\Config\BaseConfig;
use Config\App;
use App\Libraries\CI4Smarty;

require_once SYSTEMPATH . 'Config/Services.php';

class Services extends CoreServices
{
    public static function SmartyEngine($getShared = true){
        return ($getShared === true ? static::getSharedInstance('SmartyEngine') : new CI4Smarty());
    }
};

Controller to return function:

Code:

return service('SmartyEngine')->view('smarty_template.tpl');

This approach (service) avoids to load Smarty every time when your app runs. You can call service('SmartyEngine') in your controller whenever you need to run it.