How to pass data between container view and main view controller properly

Question

I'm dealing with following problem: On main VC I have a TableView, and on container view controller I have a textField. I want to add every text, I'm typing in container automatically appears as a new row on tableView in main VC

By now I'm using segue to send data from main VC to container. But what should I implement to do the same in a reverse order? I though of implementing delegate of main VC in my container view, but I have no idea how to do that properly. Or maybe there is exist more common solution.

Anyway, here is my code:

class MessageViewController: UIViewController {

    var currentUser: User!

    var containerViewController: InputTextViewController?

    @IBOutlet weak var enterMessageView: UIView!
    @IBOutlet weak var messageTableView: UITableView!
}

extension MessageViewController {

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if segue.identifier == "moveToInputText" {
            let connectContainerViewController = segue.destination as? InputTextViewController
            containerViewController = connectContainerViewController

            containerViewController?.userSendMessageTo = currentUser

        }
    }
}

extension MessageViewController: UITableViewDelegate, UITableViewDataSource {

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

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "messageCell") as! ChatMessageTableViewCell
        let data = currentUser.mesaageHistory[indexPath.row]
        cell.messageLabel.text = data.messageText

        return cell
    }
}

class InputTextViewController: UIViewController {

    @IBOutlet weak var messageTextField: UITextField!

    var userSendMessageTo: User!

    weak var delegate = MessageViewController()

    @IBAction func sendMessge(_ sender: Any) {

        handleSend()
        userSendMessageTo.mesaageHistory.append(message)

        print(userSendMessageTo.mesaageHistory[0].messageText)

        let row = userSendMessageTo.mesaageHistory.count - 1
        let insertIndexPath = IndexPath(item: row, section: 0)

        print(userSendMessageTo.mesaageHistory.count)

        delegate?.messageTableView.beginUpdates()
        delegate?.messageTableView.insertRows(at: [insertIndexPath], with: UITableViewRowAnimation.automatic)
        delegate?.messageTableView.endUpdates()

    }

}

Answer 1

Here's how to use the 'delegate' pattern properly

1. Protocol declaration & delegate member

    protocol InputTextViewControllerDelegate: class { func someFunc() func anotherFunc() } class InputTextViewController: UIViewController { weak var delegate: InputTextViewControllerDelegate? } 

2. Protocol implementation & setting the delegate property

    extension MessageViewController, InputTextViewControllerDelegate { // MARK: InputTextViewControllerDelegate // func someFunc() { } func anotherFunc() { } override func prepare(for segue: UIStoryboardSegue, sender: Any?) { if segue.identifier == "moveToInputText" { let connectContainerViewController = segue.destination as? InputTextViewController containerViewController = connectContainerViewController containerViewController } } }