code: public function actionConfirm($id, $code)
  	{
  		$user = UserIdentity::findByActivationToken($id, $code);
  
  		if ($user == NULL)
  			throw new NotFoundHttpException;
  
  		if (!empty($user)) {
  			$user->activation_token = NULL;
  			$user->status = User::STATUS_ACTIVE;
  			$user->save(FALSE);
  
  			Yii::$app->session->setFlash('success', Yii::t('user', 'Account ' . $user->email . ' has successfully been activated'));
  		} else
  			Yii::$app->session->setFlash('error', Yii::t('user', 'Account ' . $user->email . ' could not been activated. Please contact the Administrator'));
  
  		return $this->render('confirm', ['user' => $user]);
  	}
docs: Confirms user's account.
  
  @param integer $id   User Id
  @param string  $code Activation Token
  
  @return string
  @throws \yii\web\NotFoundHttpException