How to set flash message in Yii2 after denied access to controller

How to set flash message in Yii2 after denied access to controller? Here is how deny access http://www.yiiframework.com/doc-2.0/yii-filters-accesscontrol.html :


public function behaviors()

{

    return [

        'access' => [

            'class' => \yii\filters\AccessControl::className(),

            'only' => ['create', 'update'],

            'rules' => [

                // deny all POST requests

                [

                    'allow' => false,

                    'verbs' => ['POST']

                ],

                // allow authenticated users

                [

                    'allow' => true,

                    'roles' => ['@'],

                ],

                // everything else is denied

            ],

        ],

    ];

}

after this it redirects to site/login. how can I make flash message there like "This section is only for registered users"?

Question and possible answers on Stackoverflow.