How do I transition/animate color of UINavigationBar?

Question

I have been searching for how to transition/animate the barTintColor of a UINavigationBar for a while now, and I only see different answers. Some use <

Answer 1

in 10 iOS it works imperfectly :(

Subclass your navigation controller to use statusbarstyle of visible view controller:

class MyNavigationController: UINavigationController {
    override var preferredStatusBarStyle: UIStatusBarStyle {
        return visibleViewController!.preferredStatusBarStyle
    }
}

Override preferredStatusBarStyle in Root controller and add function to set styles before pop animation:

private var _preferredStyle = UIStatusBarStyle.default;
override var preferredStatusBarStyle: UIStatusBarStyle {
    get {
        return _preferredStyle
    }
    set {
        _preferredStyle = newValue
        self.setNeedsStatusBarAppearanceUpdate()
    }

}


func animateNavigationColors(){
        self.setBeforePopNavigationColors()
        transitionCoordinator?.animate(alongsideTransition: { [weak self](context) in
            self?.setNavigationColors()
            }, completion: nil)
    }

func setBeforePopNavigationColors() {
    //Override in subclasses
}

In first controller:

override func setBeforePopNavigationColors() {
    navigationController?.navigationBar.tintColor = UIColor.white
    navigationController?.navigationBar.titleTextAttributes = [NSAttributedStringKey.foregroundColor: UIColor.white]
    self.preferredStatusBarStyle = UIStatusBarStyle.lightContent
}

override func setNavigationColors(){
    navigationController?.navigationBar.barTintColor = UIColor.white
    navigationController?.navigationBar.tintColor = UIColor.black
    navigationController?.navigationBar.titleTextAttributes = [NSAttributedStringKey.foregroundColor: UIColor.black]
    navigationController?.navigationBar.barStyle = UIBarStyle.default
    self.preferredStatusBarStyle = UIStatusBarStyle.default
}

In second:

  override func setNavigationColors(){
        navigationController?.navigationBar.barTintColor = UIColor.black
        navigationController?.navigationBar.tintColor = UIColor.white
        navigationController?.navigationBar.titleTextAttributes = [NSAttributedStringKey.foregroundColor: UIColor.white]
        navigationController?.navigationBar.barStyle = UIBarStyle.black
        self.preferredStatusBarStyle = UIStatusBarStyle.lightContent
    }

Example project: https://github.com/josshad/TestNavBarTransition

Answer 2

You can overwrite the push and pop methods of UINavigationController to set the bar color. I've stored the bar color corresponding to a view controller in its navigation item with a custom subclass of UINavigationItem. The following code works for me in iOS 11 for full and for interactive transitions as well:

import UIKit

class NavigationItem: UINavigationItem {
    @IBInspectable public var barTintColor: UIColor?
}

class NavigationController: UINavigationController, UIGestureRecognizerDelegate {
    func applyTint(_ navigationItem: UINavigationItem?) {
        if let item = navigationItem as? NavigationItem {
            self.navigationBar.barTintColor = item.barTintColor
        }
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        applyTint(self.topViewController?.navigationItem)
        self.interactivePopGestureRecognizer?.delegate = self
    }
    override func pushViewController(_ viewController: UIViewController, animated: Bool) {
        applyTint(viewController.navigationItem)
        super.pushViewController(viewController, animated: animated)
    }

    override func popViewController(animated: Bool) -> UIViewController? {
        let viewController = super.popViewController(animated: animated)

        applyTint(self.topViewController?.navigationItem)
        return viewController
    }

    override func popToViewController(_ viewController: UIViewController, animated: Bool) -> [UIViewController]? {
        let result = super.popToViewController(viewController, animated: animated)

        applyTint(viewController.navigationItem)
        return result
    }

    override func popToRootViewController(animated: Bool) -> [UIViewController]? {
        let result = super.popToRootViewController(animated: animated)

        applyTint(self.topViewController?.navigationItem)
        return result
    }

    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        return true
    }

    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRequireFailureOf otherGestureRecognizer: UIGestureRecognizer) -> Bool {
        return (otherGestureRecognizer is UIScreenEdgePanGestureRecognizer)
    }
}

Note: The coordination of the color animation is done by the navigation controller