Swift: pass data to first child of NavigationController instantiate with storyboardID - swift

Question

I want to pass data to the first viewController which is embeded in navigationController.
To access this navigation controller it has a storyBoardID, I arrive at instantiate navigationController but I can not pass him data,
Here is my code:
extension UINavigationController {
func dismissAndPresentNavigationController(from storyboard: UIStoryboard?, identifier: String) {
guard let navigationController = storyboard?.instantiateViewController(withIdentifier: identifier) as? UINavigationController else { return }
print("OK")
if let nav = navigationController.navigationController?.viewControllers.first as? ChatBotViewController{
print("OK2")
}
self.dismiss(animated: false, completion: nil)
self.present(navigationController, animated: true, completion: nil)
}
}
The identifier that I put in parameter is the storyBoardID of the navigation controller.
How to transmit data to the first controller of navigationcontroller?
SOLUTION:
extension UINavigationController {
func dismissAndPresentNavigationController(from storyboard: UIStoryboard?, identifier: String, with fittoBottle: FittoBottle) {
guard let navigationController = storyboard?.instantiateViewController(withIdentifier: identifier) as? UINavigationController else { return }
if let nav = navigationController.viewControllers.first as? ChatBotViewController{
nav.fittoBottle = fittoBottle
}
self.dismiss(animated: false, completion: nil)
self.present(navigationController, animated: true, completion: nil)
}

Answer 1

After instantiating the navigation controller from the storyboard, you will be able to access the root view controller via navigationController.viewControllers.first.
guard let navigationController = storyboard?.instantiateViewController(withIdentifier: identifier) as? UINavigationController else { return }
if let chatBotViewController = navigationController.viewControllers.first as? ChatBotViewController {
chatBotViewController.fittoBottle = fittoBottle
}
self.dismiss(animated: false, completion: nil)
self.present(navigationController, animated: true, completion: nil)

Answer 2

To communicate between view controllers in an iOS app, the best way is using protocol (delegate) or Notification. In you case, extending an UINavigationController doesn't sound a good idea, because you shouldn't relay on extension methods to instance view controller and then passing any data to it, and as an extension method, it's not the responsibility for an UINavigationController to take care about ChatBotViewController or any other instanced controllers.
For my suggestion, in anywhere you want to show the ChatBotViewController, in your storyboard, create a presenting modal segue to the ChatBotViewController (which is embedded in an UINavigationController), and use performSegue(withIdentifier:sender:) to initiate the navigation controller, and override prepare(for:sender:) to set the data you want to pass in your ChatBotViewController.
Here's some codes for explaining:
import UIKit
struct FittoBottle {
}
class ChatBotViewController: UIViewController {
var fittoBottle = FittoBottle()
}
class ViewController: UIViewController {
func showChatController() {
/*
If there is any controller is presented by this view controller
or one of its ancestors in the view controller hierarchy,
we will dismiss it first.
*/
if presentedViewController != nil {
dismiss(animated: true) {
self.showChatController()
}
return
}
// Data that will be sent to the new controller
let fittoBottle = FittoBottle()
// ChatBotViewControllerSegue is the segue identifier set in your storyboard.
performSegue(withIdentifier: "ChatBotViewControllerSegue", sender: fittoBottle)
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
super.prepare(for: segue, sender: sender)
guard let navigationController = segue.destination as? UINavigationController else {
return
}
guard let chatBotController = navigationController.viewControllers.first as? ChatBotViewController else {
return
}
// Get the data from sender, if not found, create it there.
// Or if you don't pass it through sender, you can specify it here.
let fittoBottle = sender as? FittoBottle ?? FittoBottle()
chatBotController.fittoBottle = fittoBottle
}
}