huahuibao/app/mobile/controllers/MainController.php

<?php
namespace mobile\controllers;

use Yii;
use yii\web\Controller;

class MainController extends PublicController{

	public function actionIndex()
	{
		$host = Yii::$app->request->getHostInfo();
		return $this->renderPartial('index',['host'=>$host]);
	}

}