CodeIgniter load language files dynamically. User can select from dropdown menu their preferred language. Autoload this model.

language_dropdown.html

 <li class="nav-item dropdown">
                    <a class="nav-link dropdown-toggle waves-effect waves-dark"
                       href="#"
                       data-toggle="dropdown"
                       aria-haspopup="true"
                       aria-expanded="false">
                        <i class="fa fa-flag"></i> <?php echo ucwords($this->My_conf->getLanguage()); ?>
                    </a>
                    <div class="dropdown-menu dropdown-menu-right user-dd animated">
                       <?php foreach($this->My_conf->getLanguages() as $language){
                           echo anchor(uri_string().'?language='.$language,icon('flag').' '.$language,'class="dropdown-item"');
                       } ?>
                    </div>
                </li>

My_config.php

<?php if(!defined('BASEPATH')) {
    exit('No direct script access allowed');
}
//autoload this model
class My_config extends CI_Model
{

    public function __construct()
    {
        $this->setLanguage();
    }
  
  
    /**
     * @param $item
     *
     * @return bool
     */
    function session($item)
    {
        if(is_array($item)) { //means we are requesting setting session
            $this->session->set_userdata($item);
            return TRUE;
        }

      return $this->session->userdata($item);
    }
  
    /**
     * set language to session
     */
    function setLanguage()
    {
        $langFiles = $this->loadLanguageFiles();

        if(isset($_GET['language'])) {
            $lang = $_GET['language'];
            if(!in_array($lang, $this->getLanguages()))
                $this->session(['language' => config_item('language')]);
            $this->session(['language' => $lang]);
        }

        $this->lang->load($langFiles, $this->session('language'));
    }

    /**
     * @return mixed
     */
    function getLanguage()
    {
        if($this->session('language'))
            return $this->session('language');
        return config_item('language');
    }

    function getLanguages()
    {
        $dir = new DirectoryIterator(APPPATH.'language');
        $languages = [];
        foreach ($dir as $fileinfo) {
            if($fileinfo->isDir() && !$fileinfo->isDot()) {
                $languages[] = $fileinfo->getFilename();
            }
        }
        return $languages;
    }

    /**
     * @param array $replace
     *
     * @return mixed
     */
    function loadLanguageFiles(Array $replace = [])
    {
        static $autoload;

        if(empty($autoload)) {
            $file_path = APPPATH.'config/autoload.php';
            $found = FALSE;
            if(file_exists($file_path)) {
                $found = TRUE;
                require($file_path);
            }
            if(file_exists($file_path = APPPATH.'config/'.ENVIRONMENT.'/autoload.php')) {
                require($file_path);
            } elseif(!$found) {
                set_status_header(503);
                echo 'The configuration file does not exist.';
                exit(3); // EXIT_CONFIG
            }

            // Does the $config array exist in the file?
            if(!isset($autoload) OR !is_array($autoload)) {
                set_status_header(503);
                echo 'Your config file does not appear to be formatted correctly.';
                exit(3); // EXIT_CONFIG
            }
        }

        // Are any values being dynamically added or replaced?
        foreach ($replace as $key => $val) {
            $autoload[$key] = $val;
        }
        return $autoload['language'];
    }
}