Set Button Title not showing on UI in Swift - swift

Question

What I want to achieve?
I have 2 UITableViewController : AddCardVC and ListDeckController. I want to pass selected Deck in ListDeckController to AddCardVC then updateUI on AddCardVC
My code: (I'm building on Swift 5, iOS 13)
ListDeckController.swift:
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let storyboard = UIStoryboard(name: "Main", bundle: nil)
if let addCardVC = storyboard.instantiateViewController(withIdentifier: "AddCard") as? AddCardVC {
if let deck = allDecks?[indexPath.row] {
addCardVC.selectedDeck = deck
}
}
self.navigationController?.popViewController(animated: true)
}
AddCardVC.swift:
var selectedDeck: Deck?
{
didSet {
viewWillAppear(true)
}
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
if let deck = selectedDeck {
//Update UI
self.chooseDeckButton.setTitle(deck.name, for: .normal)
print(chooseDeckButton.titleLabel?.text ?? "")
self.tableView.reloadData()
}
}
What happend?
After I got selected Deck in AddCardVC, the console print out chooseDeckButton.titleLabel?.text = "My Deck" which is what I want. But The button title on UI is "Choose your deck"
Console image Button on UI
So, why the setButtonTitle not showing on UI in my case?
Thank you for your time

Answer 1

First, create a protocol for DeckDelegate
protocol SelectedDeckDelegate {
func didSelectDeck(selectedDeck : Deck)
}
Now in your ListDeckController.swift, implement the delegate
var deckDelegate : SelectedDeckDelegate?
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath)
{
if let deck = allDecks?[indexPath.row] {
deckDelegate?.didSelectDeck(selectedDeck: deck)
self.navigationController?.popViewController(animated: true)
} else {
print("deck is empty")
}
}
And in your AddCardVC, when navigating to ListDeckController, assign the delegate to self
// Make AddCardVC conform to SelectedDeckDelegate
class AddCardVC : UIViewController, SelectedDeckDelegate {
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
if let deck = selectedDeck {
//Update UI
self.chooseDeckButton.setTitle(deck.name, for: .normal)
print(chooseDeckButton.titleLabel?.text ?? "")
self.tableView.reloadData()
}
}
// assign the delegate to self here
#IBAction func selectDeckBtnAction(_ sender : Any) {
let vc = storyboard.instantiateViewController(withIdentifier: "ListDeckController") as? ListDeckController
vc.deckDelegate = self
self.navigationController?.pushViewController(vc, animated: true)
}
// this will get called whenever selectedDeck is updated from ListDeckController
func didSelectDeck(selectedDeck: Deck) {
self.selectedDeck = selectedDeck
chooseDeckButton.setTitle(selectedDeck.name , for: .normal)
}
}