Resetting the navigation stack on a UITabBarController doesn't work - ios

Question

I'm trying to reset the navigation stack on a subclass of UITabViewController embedded in a UINavigationController but it doesn't work.
My navigation stack, which I create programmatically, is like this:
UINavigationController => ControllerA (a subclass of UIViewController) =>
ControllerB (a subclass of UIViewController) => ControllerC (a
subclass of UITabBarController).
When users press on the "Back" button or swipe back from ControllerC, the app should go back to ControllerA, not ControllerB.
Usually, when I want to reset the navigation stack, I do this in the Controller's viewDidLoad() method:
override func viewDidLoad() {
super.viewDidLoad()
// usually work, but not in a subclass of UITabBarController as self.navigationController is nil
if let navigationController = self.navigationController {
// keep only the root controller (0) and the current controller
navigationController.viewControllers = [navigationController.viewControllers[0], self]
}
}
but this doesn't work in ControllerC (the subclass of UITabViewController) as self.navigationController is nil.
If I do this instead (still in ControllerC's viewDidLoad() method):
/// ControllerC's viewDidLoad
override func viewDidLoad() {
super.viewDidLoad()
if let navigationController = UIApplication.shared.keyWindow?.rootViewController as? UINavigationController {
// keep only the root controller (0) and the current controller
navigationController.viewControllers = [navigationController.viewControllers[0], self]
}
}
This works, but then there is no animation between ControllerB and ControllerC when I do:
controllerB.navigationController?.pushViewController(ControllerC(), animated: true)
I also tried to override ControllerC's viewWillDisappear() method:
/// ControllerC's viewWillDisappear
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
if self.isMovingFromParent {
if let navigationController = UIApplication.shared.keyWindow?.rootViewController as? UINavigationController {
navigationController.popToRootViewController(animated: true)
}
}
This works, but ControllerB is briefly visible before ControllerA is shown.
Any help would be greatly appreciated!

Answer 1

In the ControllerC instead of trying to override viewWillDisappear() method you can override viewDidAppear() like that:
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
if let navC = UIApplication.shared.keyWindow?.rootViewController as? UINavigationController {
// keep only the root controller (0) and the current controller
navC.viewControllers = [navC.viewControllers[0], self]
}
}
And ControllerB won’t be briefly visible before ControllerA when you navigate backwards.