方式一：
controller 中

class BlogController extends Controller{
    public $layout = 'newlayout';
    public $menu = "";
    public function actionIndex(){

        $this->menu = 'menumenu';
        return $this->render('index');
    }
}

layout 中

<?= $this->context->menu ?>

方式2

controller 中

class BlogController extends Controller{
    public $layout = 'newlayout';
    public function actionIndex(){
        $view = YII::$app->view;
        $view->params['menu'] = "menumenu";
        return $this->render('index');
    }
}

layout 中

$this->params['menu']