Segue not working after setting up custom navigationBar - ios

Question

I am performing a segue from my loadVC to containterVC in which I set up a navigationController and set it's rootViewController to mainVC
Code in viewDidLoad in containterVC:
override func viewDidLoad() {
super.viewDidLoad()
mainVC = UIStoryboard.mainVC() //This is an extension to UIStoryboard
//Setting up the delegate:
mainVC.delegate = self
//rootViewController - ten najbardziej na dole
myNavigationController = UINavigationController(rootViewController: mainVC)
//Storing the root view as currentViewController:
self.currentViewController = mainVC
myNavigationController.addChildViewController(mainVC)
self.view.addSubview(myNavigationController.view)
addChildViewController(myNavigationController)
myNavigationController.didMoveToParentViewController(self)
//Trying to set up the navigation bar
let bar = myNavigationController.navigationBar
//Navigation bars:
bar.barTintColor = UIColor.blackColor()
bar.tintColor = UIColor.whiteColor()
bar.translucent = false
}
I launch the project. And? Everything works properly.
Then I try to add these under "bar.translucent = false" line:
print("statement1")
let menuButton = UIBarButtonItem(title: "Menu", style: UIBarButtonItemStyle.Plain, target: self, action: "")
print("statement2")
let item = myNavigationController.navigationItem
print("statement3")
item.leftBarButtonItem = menuButton
print("statement4")
bar.items = [item]
print("statement5")
After launching the project print statements up to 4 are displayed and the 5th is not. So it seems that the segue between loadVC and containterVC is done, but I don't see the mainVC screen that was set up as a rootViewController.
When I delete "bar.items = [item]" line the project is run as it should be, but there is no "Menu" button in the navigation bar.
What am I doing wrong?

Answer 1

You can just use a "container view" from the storyboard and embed a UINavigationController with your mainVC directly within the storyboard.
Anyway i think that myNavigationController.addChildViewController(mainVC) not necessary.
Also the bar items should be set to the mainVC's navigationItem, not the navigationController's one.
Also you did not mention what kind of segue are you using.