UINavigation controller: present and dismiss programmatically - swift

Question

I have a TableViewController which I want to present modally and I need it to have a NavigationBar.
To get that navbar, I have an embedded UINavigationController and as far as I know, that UINavigationController is what I have to present modally, so that's what I've done.
Everything works just fine, but I can't manage to dismiss that controller properly. Here is what I've got so far:
func presentErrorMessages(errorMessages: [String]) {
let storyBoard: UIStoryboard = UIStoryboard(name: "Message", bundle: nil)
let infoMessagesNavigationViewController = storyBoard.instantiateViewController(withIdentifier: "InfoMessagesNavigation") as! ModalNavigationController
let infoMessagesTableViewController = infoMessagesNavigationViewController.viewControllers[0] as! InfoMessagesTableViewController
infoMessagesTableViewController.errorMessages = errorMessages
self.navigationController?.present(infoMessagesNavigationViewController, animated: true)
}
I use that to present ModalNavigationController, and this to dismiss it:
class ModalNavigationController: BaseNavigationController {
var backNavItem = UINavigationItem()
var okNavItem = UINavigationItem()
override func viewDidLoad() {
super.viewDidLoad()
let backButton = UIBarButtonItem(title: "Back", style: .plain, target: self, action: #selector(dismissModal))
backNavItem.leftBarButtonItem = backButton
...
var items = [UINavigationItem]()
items.append(backNavItem)
self.navigationBar.items = items
}
#objc func dismissModal() {
self.dismiss(animated: true)
}
}
When I press that back button, there is no change but the navbar which gets blank (with no title). I have the feeling that the application just 'forgets' what is the NavigationController used before the new one is presented.
How can I solve this?

Answer 1

Try something like this:
override func viewDidLoad() {
super.viewDidLoad()
self.navigationItem.leftBarButtonItem = UIBarButtonItem(title: "Back", style: .done, target: self, action: #selector(dismissModal))
...
}
#objc func dismissModal() {
self.dismiss(animated: true, completion: nil)
}

Answer 2

I managed to solve the problem by placing and invoking the dismissfunction on my TableViewController rather than my NavigationController:
...
public func setBackButton(){
if self.navigationController != nil {
let item = UIBarButtonItem(title: "Back", style: .plain, target: self, action: #selector(dismissModal))
self.navigationItem.leftBarButtonItem = item
}
}
#objc func dismissModal() {
self.dismiss(animated: true)
}