How can you reload a ViewController after dismissing a modally presented view controller in Swift?

Question

I have a first tableViewController which opens up a second tableViewcontroller upon clicking a cell. The second view controller is presented modally (Show Detail segue) and is dismissed with:

self.dismissViewControllerAnimated(true, completion: {})

At this point, the second view controller slides away and reveals the first view controller underneath it. I would then like to reload the first view controller. I understand that this may require use of delegate functions, but not sure exactly how to implement it

Answer 1

Swift 5:

You can access the presenting ViewController (presentingViewController) property and use it to reload the table view when the view will disappear.

class: FirstViewController {
    var tableView: UITableView

    present(SecondViewController(), animated: true, completion: nil)
}

In your second view controller, you can in the viewWillDisappear method, add the following code:

class SecondViewController {
    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)

        if let firstVC = presentingViewController as? FirstViewController {
            DispatchQueue.main.async {
                firstVC.tableView.reloadData()
            }
        }
    }
}

When you dismiss the SecondViewController, the tableview of the FirstViewController will reload.

Answer 2

I solved it a bit differently since I don't want that dependancy.

And this approach is intended when you present a controller modally, since the presenting controller wont reload when you dismiss the presented.

Anyway solution!

Instead you make a Singleton (mediator)

protocol ModalTransitionListener {
    func popoverDismissed()
}

class ModalTransitionMediator {
    /* Singleton */
    class var instance: ModalTransitionMediator {
        struct Static {
            static let instance: ModalTransitionMediator = ModalTransitionMediator()
        }
        return Static.instance
    }

private var listener: ModalTransitionListener?

private init() {

}

func setListener(listener: ModalTransitionListener) {
    self.listener = listener
}

func sendPopoverDismissed(modelChanged: Bool) {
    listener?.popoverDismissed()
}
}

Have you Presenting controller implement the protocol like this:

class PresentingController: ModalTransitionListener {
//other code
func viewDidLoad() {
    ModalTransitionMediator.instance.setListener(self)
}
//required delegate func
func popoverDismissed() {
    self.navigationController?.dismissViewControllerAnimated(true, completion: nil)
    yourTableViev.reloadData() (if you use tableview)
}
}

and finally in your PresentedViewController in your viewDid/WillDisappear func or custom func add:

ModalTransitionMediator.instance.sendPopoverDismissed(true)