Different appearances in different UINavigationControllers

Question

In iOS 11 I'm currently changing the back button for my navigation controllers like this:

UINavigationBar.appearance().backIndicatorImage = whiteBackButtonImage!.withRenderingMode(.alwaysOriginal)
UINavigationBar.appearance().backIndicatorTransitionMaskImage = whiteBackButtonImage!.withRenderingMode(.alwaysOriginal)

That seems to work fine, the problem is when I want to differentiate between two kind of UINavigationControllers using different back images :

let whiteNavigationBarAppearance = UINavigationBar.appearance(whenContainedInInstancesOf: [WhiteNavigationController.self])
whiteNavigationBarAppearance.backIndicatorImage = greenBackButtonImage!.withRenderingMode(.alwaysOriginal)
whiteNavigationBarAppearance.backIndicatorTransitionMaskImage = greenBackButtonImage!.withRenderingMode(.alwaysOriginal)

let greenNavigationBarAppearance = UINavigationBar.appearance(whenContainedInInstancesOf: [GreenNavigationController.self])
greenNavigationBarAppearance.backIndicatorImage = whiteBackButtonImage!.withRenderingMode(.alwaysOriginal)
greenNavigationBarAppearance.backIndicatorTransitionMaskImage = whiteBackButtonImage!.withRenderingMode(.alwaysOriginal)

With the second approach, the regular back button is shown, so somehow it doesn't recognise the changes. Does anyone know what's wrong in my approach?

Do you use storyboards? Have you assigned appropriate classes to your navigation controllers? — Kamil Szostakowski, Oct 18 '17 at 17:45
No, I'm creating the navigation controllers programatically. — tonik12, Oct 19 '17 at 08:09

score 3 · Answer 1 · answered Oct 19 '17 at 22:16

I have recreated your scenario on the side project and the snippet you presented works just fine. I think there may be something in your view controllers hierarchy.

This is how I build the hierarchy. ViewController has a button which pushes another UIViewController on the navigation stack.

let redViewController = ViewController()
redViewController.view.backgroundColor = .red

let greenViewController = ViewController()
greenViewController.view.backgroundColor = .green

let red = RedNavigationController(rootViewController: redViewController)
red.tabBarItem = UITabBarItem(tabBarSystemItem: .bookmarks, tag: 1)

let green = GreenNavigationController(rootViewController: greenViewController)
green.tabBarItem = UITabBarItem(tabBarSystemItem: .contacts, tag: 2)

let tabBarController = UITabBarController()
tabBarController.setViewControllers([red, green], animated: false)
tabBarController.selectedIndex = 0

This is how I set up the appearance.

let image1 = UIImage(named: "Button")!.withRenderingMode(.alwaysOriginal)
let image2 = UIImage(named: "Button2")!.withRenderingMode(.alwaysOriginal)

let red = UINavigationBar.appearance(whenContainedInInstancesOf: [RedNavigationController.self])
red.backIndicatorImage = image1
red.backIndicatorTransitionMaskImage = image1

let green = UINavigationBar.appearance(whenContainedInInstancesOf: [GreenNavigationController.self])
green.backIndicatorImage = image2
green.backIndicatorTransitionMaskImage = image2

And this is the result

Different appearances in different UINavigationControllers

1 Answers1