在null上调用成员函数View（）

My IF in this method forward to view variable $this->session['stCeneo'].

public function onCheckoutPostDispatch(\Enlight_Event_EventArgs $args)
    {
        $this->subject = $args->getSubject();


   if ('finish' === $this->subject->Request()->getActionName()) {
            $this->saveRequestToSession();

            $view = $subject->View(); //error?
            $view->assign('stCeneo', $this->session['stCeneo']); //error?

        }

$this->session['stCeneo'] is implemented in saveRequestToSession().

private function saveRequestToSession()
{
    if ($this->subject->Request()->getParam('stOpineo') !== null) {
        $this->session['stOpineo'] = $this->subject->Request()->getParam('stOpineo') ? true : false;
    }

    if ($this->subject->Request()->getParam('stCeneo') !== null) {
        $this->session['stCeneo'] = $this->subject->Request()->getParam('stCeneo') ? true : false;
    }
}

SO I don't know, why I have a error in my line commented:

Uncaught Error: Call to a member function View() on null

Okay, I resolved this problem. I write:

$this->subject->View()->assign('stCeneo', $this->session['stCeneo']);