Yii2-Session超时设置无效问题处理

<?php

        $lifeTime = 5;  

        //因修改了SESSION_ID，设置过期时间必须指定session_name

        //session_set_cookie_params($lifeTime, '/');   //默认session name:PHPSESSIONID
        

        //session_start();        

        //setcookie(session_name(), session_id(), time() + $lifeTime, '/');  
//推荐使用，必须在session_start() 之后运行

        

        /* if(!isset($_SESSION['signup_sms'])) {

            $_SESSION['signup_sms'] = 'wccc1';

            echo 'set session. ';

        } */

        

        /* 无效，why?  不能自动识别修改过的PHPSESSIONID？

        Yii::$app->session->setCookieParams([

                'lifetime' => $lifeTime,

                'path' => '/',

            ]

        ); */

        

        //Cannot use isset() on the result of an expression (use "null !== expression" instead)

        if (null == Yii::$app->session->get('signup_sms')){

            Yii::$app->session->set('signup_sms', 'wccc2');            

            echo 'set session. ';

        }

        setcookie(session_name(), session_id(), time() + $lifeTime, '/');

        print_r(Yii::$app->session->get('signup_sms').'<br>');

        //Yii::$app->session->removeAll();

        //Yii::$app->session->close();

        exit();