New item não funciona

Boa tarde! Assim que eu inseri o conteúdo dessa atividade no código, começou a dar erro. Não faço ideia de qual seja o problema hah

ViewController

@IBOutlet var tableView : UITableView?

    func add(_ item: Item) {
        items.append(item)
        if let table = tableView{
            table.reloadData()
        }
    }

    override func viewDidLoad() {
        let newItemButton = UIBarButtonItem(title: "new item", style: UIBarButtonItemStyle.plain, target: self, action: #selector(showNewItem))

        navigationItem.rightBarButtonItem = newItemButton
    }

    @objc func showNewItem(){
        let newItem = NewItemViewController(delegate: self) //poderia passar algo dentro tipo um putExtra
        if let navigation = navigationController{
            navigation.pushViewController(newItem, animated: true)
        }
    }

    //numero de linhas na table
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return items.count
    }

    //oq vai ter em cada celula da linha da table
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let row = indexPath.row
        let item = items[row]
        let cell = UITableViewCell(style: UITableViewCellStyle.default, reuseIdentifier:nil)
        cell.textLabel!.text = item.name

        return cell
    }

NewItemViewController

var delegate:AddAnItemDelegate?

    init(delegate: AddAnItemDelegate){
        super.init(nibName: "NewItemViewController", bundle: nil)
        self.delegate = delegate
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }

    @IBOutlet var nameField : UITextField?
    @IBOutlet var caloriesField : UITextField?


    @IBAction func addNewItem(){

        let name = nameField!.text
        let calories = Double(caloriesField!.text!)

        if (name == nil || calories == nil || delegate == nil) {
            return
        }

        let item = Item(name: name!, calories: calories!)
        delegate!.add(item)

        if let navigation = navigationController{
            navigation.popViewController(animated: true)
        }
    }

AddAnItemDelegate

import Foundation

protocol AddAnItemDelegate {
    func add(_ item: Item)
}

Grata desde já pela ajuda!