selectLanguage example

// Save post parameters starting with 'c_' to session     $params = $app->request()->params();
    foreach ($params as $key => $value) {
        if (strpos($key, 'c_') !== false) {
            $_SESSION['parameters'][$key] = $antiXss->xss_clean($value);
        }
    }
}

prefixSessionVars($app, $container);
$selectedLanguage = selectLanguage($container->offsetGet('config')['languages']);
$translations = require __DIR__ . "/../data/lang/$selectedLanguage.php";

$container->offsetSet('translations', $translations);

/** @var TranslationService $translationService */
$translationService = $container->offsetGet('translation.service');

$container->offsetSet('install.language', $selectedLanguage);

/** @var MenuHelper $menuHelper */
$menuHelper = $container->offsetGet('menu.helper');