将 php 处理会话的函数转换为 codeigniter

converting php functions that deal with sessions into codeigniter

我有两个处理会话的函数,我需要将它们转换成 codeigniter way.I 成功完成了第一个 但我被困在第二个访问会话数组索引

第一个函数:

function addItem($pid,$qty=1){
$_SESSION['basket'][$pid]['kty']=$qty;
}

变成了:

function addItem($pid,$qty=1){
    $arr=array($pid=>array('kty'=>$qty));
        $this->session->set_userdata('basket',$arr);

}

第二个函数:

function removeItem($pid,$qty=null){
        if($qty != null && $qty < $_SESSION['basket'][$pid]['kty']){

        $_SESSION['basket'][$pid]['kty']=($_SESSION['basket'][$pid]['kty']-$qty);
        }else{
        $_SESSION['basket'][$pid]=null;
        unset($_SESSION['basket'][$pid]);
        }

    }

如何用 codeigniter 方式重写第二个函数?

function removeItem($pid,$qty=null){
        if($qty != null && $qty < $_SESSION['basket'][$pid]['kty']){

        $_SESSION['basket'][$pid]['kty']=($_SESSION['basket'][$pid]['kty']-$qty);
        }else{
        $_SESSION['basket'][$pid]=null;
        unset($_SESSION['basket'][$pid]);
        }

    }

将 $_SESSION 更改为 $this->session->userdata for ex :

$_SESSION['basket'][$pid]['kty'] 
to 
$this->session->userdata['basket'][$pid]['kty']