class  ControllerA: UIViewController {

    override var inputAccessoryView: UIView? {
        return saveView
    }

    override var canBecomeFirstResponder: Bool {
        return true
    }

    @IBAction func openVCB(_ sender: UIButton) {

    let controllerB = controllerB.instantiate(fromAppStoryboard: .main)
        let navigationController = UINavigationController(rootViewController: controllerB)
        navigationController.navigationBar.isTranslucent = false
        self.present(navigationController, animated: true)
    }
}

class  ControllerB: UIViewController {

    override var inputAccessoryView: UIView? {
        return nil
    }

    override var canBecomeFirstResponder: Bool {
        return false
    }

}