CCookieCollection

public function __construct(CHttpRequest $request)
{
    $this->_request=$request;
    $this->copyfrom($this->getCookies());
    $this->_initialized=true;
}

public function add($name,$cookie)
{
    if($cookie instanceof CHttpCookie)
    {
        $this->remove($name);
        parent::add($name,$cookie);
        if($this->_initialized)
            $this->addCookie($cookie);
    }
    else
        throw new CException(Yii::t('yii','CHttpCookieCollection can only hold CHttpCookie objects.'));
}

protected function addCookie($cookie)
{
    $value=$cookie->value;
    if($this->_request->enableCookieValidation)
        $value=Yii::app()->getSecurityManager()->hashData(serialize($value));
    if(version_compare(PHP_VERSION,'5.2.0','>='))
        setcookie($cookie->name,$value,$cookie->expire,$cookie->path,$cookie->domain,$cookie->secure,$cookie->httpOnly);
    else
        setcookie($cookie->name,$value,$cookie->expire,$cookie->path,$cookie->domain,$cookie->secure);
}

protected function getCookies()
{
    $cookies=array();
    if($this->_request->enableCookieValidation)
    {
        $sm=Yii::app()->getSecurityManager();
        foreach($_COOKIE as $name=>$value)
        {
            if(is_string($value) && ($value=$sm->validateData($value))!==false)
                $cookies[$name]=new CHttpCookie($name,@unserialize($value));
        }
    }
    else
    {
        foreach($_COOKIE as $name=>$value)
            $cookies[$name]=new CHttpCookie($name,$value);
    }
    return $cookies;
}

public function getRequest()
{
    return $this->_request;
}

public function remove($name,$options=array())
{
    if(($cookie=parent::remove($name))!==null)
    {
        if($this->_initialized)
        {
            $cookie->configure($options);
            $this->removeCookie($cookie);
        }
    }

    return $cookie;
}

protected function removeCookie($cookie)
{
    if(version_compare(PHP_VERSION,'5.2.0','>='))
        setcookie($cookie->name,'',0,$cookie->path,$cookie->domain,$cookie->secure,$cookie->httpOnly);
    else
        setcookie($cookie->name,'',0,$cookie->path,$cookie->domain,$cookie->secure);
}