获取yii2中重定向请求的URL？

Question

Sorry for my English, but what I'm trying to say is explained below.

I have a controller say ControllerCard which has an action like this.

function actionScanCard()
{
    ...
    $this->redirect('/transaction/redeem');
    ...
}

In other controllers, ControllerTransaction, I am trying to get that it comes/redirected from /card/scan-card

function actionRedeem()
{
    $redirectFrom = ????;
    if ($redirectFrom === '/card/scan-card')
    {
        // some actions
    }
    else
        throw new ForbiddenHttpException('Must scan card!');
}

How do I get this $redirectFrom value with Yii2?