Protocol do Swifit não funciona

class ListItensController: UITableViewController, ViewControllerDelegate {
    var refeicoes: [Meal] = []

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return refeicoes.count
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = UITableViewCell(style: .default, reuseIdentifier: nil)
        cell.textLabel?.text = refeicoes[indexPath.row].name
        return cell
    }

    func add(_ refeicao: Meal){
        refeicoes.append(refeicao)
        tableView.reloadData()
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if(segue.identifier == "addMealSegue"){
            if let viewController = segue.destination as? ViewController {
                viewController.delegate = self
            }
        }
    }
}

/*======================*/

protocol ViewControllerDelegate {
    func add(_ refeicao: Meal)
}

class ViewController: UIViewController {
    @IBOutlet weak var nameTf: UITextField?
    @IBOutlet weak var noteTf: UITextField?

    var delegate: ViewControllerDelegate?

    @IBAction func add(_ sender: Any) {
        if let name = nameTf?.text, let note = noteTf?.text {
            if let noteL = Int(note) {
                let meal: Meal = Meal(name: name, note: noteL)
                delegate?.add(meal)
                navigationController?.popViewController(animated: true)
            }

        }
    }
}

O protocol não está funcionando, alguém pode me ajudar?