How to send a notification using session->setFlash to another user?

Question

Yii

I use alert from v-kartik. Everything works, but ...
It is necessary that when sending a message, a notification is received not by the sender, but by the recipient.
in controller:

Yii::$app->getSession(тут должен быть ид юзера?)->setFlash('message, [
 ]);
 return $this->redirect(['view', 'id' => $model->id]);
} else {
 return $this->render('create', [
             'model' => $model,
 ]);
}

in view:

<?php foreach (Yii::$app->session->getFlash(ид юзера) as $message):; ?>

<?php
echo Growl::widget([
    'type' => Growl::TYPE_GROWL,
    'title' => 'Roar!',
    'icon' => '/images/icon.png',
    'body' => 'This is a default growling alert you requested for.',
    'showSeparator' => false,
    'delay' => 6000,
    'pluginOptions' => [
        'icon_type'=>'image',
        'placement' => [
            'from' => 'top',
            'align' => 'right',
        ],
        'template' => [
            'icon_type' => 'image'
        ]
    ]
]);
?>
        <?php endforeach; ?>

Answer 1

using session->setFlash to another user?

No way, session->setFlash uses the session of the current user, and no one else. In your case, you need to enter some kind of push server and send notifications to it.