Gajus\Fuss\SignedRequest::getUserId PHP Method

User ID when user access token is in or can be derived from the signed request.

public getUserId ( ) : null \| integer
return	null \| integer

    public function getUserId()
    {
        return isset($this->signed_request['user_id']) ? (int) $this->signed_request['user_id'] : null;
    }

SignedRequest