src/Controller/Component/AuthUtilsComponent.php
public function checkRememberMeCookie()
    {
        if (!$this->loggedIn() && $this->Cookie->read('User.id')) {
            return $this->Cookie->read('User.id');
        }
        return false;
    }
public function checkRememberMeCookie()
    {
        if (!$this->loggedIn() && $this->Cookie->read('User.id')) {
            return $this->Cookie->read('User.id');
        }
        return false;
    }
Check if a remeber me cookie exists and login the user

@return mixed User ID on success, false if no valid cookie