获取yii2中重定向请求的URL？

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?

You could use the remember() & previous() methods in yii\helpers\BaseUrl.

function actionScanCard()
{
    ...
    \yii\helpers\Url::remember();
    $this->redirect('/transaction/redeem');
    ...
}

in TransactionController (or other)

function actionRedeem()
{
    $url = \yii\helpers\Url::previous();
    if($url === Url::to('card/scan-card')) {
        // some actions
    } else{}
}