I am trying to using a custom delegate in swift but when I want to call its methods, it did not get called

Question

I have been searching for how the delegate works and I tried to do it in my project. Unfortunately, the delegate method I implement does not get called ever. I am trying to do a slide-out navigation panel. so what I did is that I put two uicontainerviews, one is for slide-out navigation panel and the other for main view controller enter image description here

The code is that For main view controller

protocol MainViewControllerDelegate {
    func toggleSideMenu()
}

class MainViewController: UIViewController {

    var delegate: MainViewControllerDelegate?

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    // MARK: - Slide Action

    @IBAction func slideMenuTapped(_ sender: UIBarButtonItem){
        delegate?.toggleSideMenu()
        print("Slide Menu has been tapped")
    }
}

For container view controller

class ContainerVC: UIViewController {
    @IBOutlet weak var SideMenuConstraint: NSLayoutConstraint!
    @IBOutlet weak var slideMenuContainer: UIView!
    @IBOutlet weak var mainViewContainer: UIView!

    var mainViewController: MainViewController?

    var isSideMenuOpened = false

    override func viewDidLoad() {
        super.viewDidLoad()

        mainViewController = UIStoryboard.mainViewController()
        mainViewController?.delegate = self
    }
}

extension ContainerVC: MainViewControllerDelegate{
    func toggleSideMenu() {
        print("It works")
        if isSideMenuOpened{
            isSideMenuOpened = false
            SideMenuConstraint.constant = -260
            mainViewContainer.layer.shadowOpacity = 0
        } else {
            isSideMenuOpened = true
            SideMenuConstraint.constant = 0
            mainViewContainer.layer.shadowOpacity = 0.59
        }
        UIView.animate(withDuration: 0.3) {
            self.view.layoutIfNeeded()
        }
    }
}

extension UIStoryboard{
    static func mainStoryboard() -> UIStoryboard { return UIStoryboard(name: "Main", bundle: Bundle.main) }
    static func mainViewController() -> MainViewController? {
        return mainStoryboard().instantiateViewController(withIdentifier: "MainViewController") as? MainViewController
    }
}

Please let know what's wrong

Refer to this link for more info about how to declare a delegate in swift: https://stackoverflow.com/a/25792213/1091539 — Mutawe, Mar 11 '18 at 08:06
initialize it like this, delegate = MainViewControllerDelegate() — Ashik, Mar 11 '18 at 08:19
@Ashik I did that but I got this error "'MainViewControllerDelegate' cannot be constructed because it has no accessible initializers" — Faisal Alkhotaifi, Mar 11 '18 at 08:30

Sweeper · Answer 1 · 2018-03-11T08:32:02.420

0

Here is where you got wrong:

mainViewController = UIStoryboard.mainViewController()
mainViewController?.delegate = self

this mainViewController is not the same as the child of the container view controller, so setting its delegate doesn't really do anything.

You need to first get the VC that is the child of the container view controller:

mainViewController = self.childViewControllers.last as! MainViewController
mainViewController.delegate = self

edited Mar 11 '18 at 08:32

answered Mar 11 '18 at 08:13

Sweeper

213,210
22
193
313

@FaisalAlkhotaifi Sorry, I thought your container is a child of a parent, fixed now. – Sweeper Mar 11 '18 at 08:32

score 0 · Accepted Answer · answered Mar 11 '18 at 10:19

0

I think the reason is that you embed your main view controller in navigation controller :

let navigationController = self.childViewControllers.last as! UINavigationController
let mainViewController = navigationController.topViewController as! MainViewController
mainViewController?.delegate = self

answered Mar 11 '18 at 10:19

Qi Hao

36
3

Yup, that is right. I tried it and it worked. Thanks! – Faisal Alkhotaifi Mar 11 '18 at 11:48

I am trying to using a custom delegate in swift but when I want to call its methods, it did not get called

2 Answers2