controllers/RegistrationController.php
public function actionConfirm($id, $code)
    {
        $user = $this->finder->findUserById($id);

        if ($user === null || $this->module->enableConfirmation == false) {
            throw new NotFoundHttpException;
        }

        $user->attemptConfirmation($code);

        return $this->render('/message', [
            'title'  => \Yii::t('user', 'Account confirmation'),
            'module' => $this->module,
        ]);
    }
public function actionConfirm($id, $code)
    {
        $user = $this->finder->findUserById($id);

        if ($user === null || $this->module->enableConfirmation == false) {
            throw new NotFoundHttpException;
        }

        $user->attemptConfirmation($code);

        return $this->render('/message', [
            'title'  => \Yii::t('user', 'Account confirmation'),
            'module' => $this->module,
        ]);
    }
Confirms user's account. If confirmation was successful logs the user and shows success message. Otherwise
shows error message.
@param  integer $id
@param  string  $code
@return string
@throws \yii\web\HttpException