iOS 10 barTintColor动画

Question

I've noticed a change in the way bar tint color animates in ios 10. I've created a sample project outlining the change: Github: ios10BarTintDemo

Basically on ios 9 the barTintColor animates smoothly using [UIViewControllerTransitionCoordinator animateAlongsideTransition]

but on ios 10 the animations are much less smooth and when popping a view controller doesn't animate at all, I've tried adding [self.navigationController.navigationBar layoutIfNeeded] as mentioned in some similar answers but this doesn't seem to have any effect when pushing/popping controllers.

Answer 1

UPDATE

I've tested in iOS 10.3 and I think the problem was fixed. And transitionCordinator is no need anymore. I think the animation is smooth. Please check my project on github or look at this code:

class ViewControllerA: UIViewController {

    override func loadView() {
        super.loadView()
        title = "A"
        view.backgroundColor = .white
        navigationItem.rightBarButtonItem = UIBarButtonItem(title: "NEXT", style: .plain, target: self, action: #selector(self.showController))
    }

    override func viewWillAppear(_ animated: Bool) {
        setColors()
        super.viewWillAppear(animated)
    }

    func showController() {
        navigationController?.pushViewController(ViewControllerB(), animated: true)
    }

    private func setColors() {
        navigationController?.navigationBar.tintColor = .black
        navigationController?.navigationBar.barTintColor = .red
        navigationController?.navigationBar.isTranslucent = false
    }
}




class ViewControllerB: UIViewController {

    override func loadView() {
        super.loadView()
        title = "B"
        view.backgroundColor = .white
    }

    override func viewWillAppear(_ animated: Bool) {
        setColors()
        super.viewWillAppear(animated)
    }

    override func willMove(toParentViewController parent: UIViewController?) {
        if parent == nil {
            navigationController?.navigationBar.barTintColor = .red
        }
        super.willMove(toParentViewController: parent)
    }


    private func setColors() {
        navigationController?.navigationBar.tintColor = .black
        navigationController?.navigationBar.barTintColor = .blue
        navigationController?.navigationBar.isTranslucent = false
    }
}

============================================================================================================================================================================================================================================================================================================

To achieve this kind of animation you should use UIViewControllerTransitionCoordinator as Apple documentation say it is :

An object that adopts the UIViewControllerTransitionCoordinator protocol provides support for animations associated with a view controller transition.(...)

So every UIViewController has own transitionController . To get this you should call in the UIViewControllerClass :

self.transitionCoordinator()

From documentation :

Returns the active transition coordinator object.

So to get the result that you want you should implement animateAlongsideTransition method in viewController transitionCoordinatior. Animation works when you click backButton and swipe to back.

Example :

First Controller :

class ViewControllerA: UIViewController {

    override func loadView() {
        super.loadView()
        title = "A"
        view.backgroundColor = .white
        navigationItem.rightBarButtonItem = UIBarButtonItem(title: "NEXT", style: .plain, target: self, action: #selector(self.showController))
        setColors()
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        animate()
    }

    func showController() {
        navigationController?.pushViewController(ViewControllerB(), animated: true)
    }

    private func animate() {
        guard let coordinator = self.transitionCoordinator else {
            return
        }

        coordinator.animate(alongsideTransition: {
            [weak self] context in
            self?.setColors()
        }, completion: nil)
    }

    private func setColors() {
        navigationController?.navigationBar.tintColor = .black
        navigationController?.navigationBar.barTintColor = .red
    }
}

Second Controller:

class ViewControllerB : UIViewController {

    override func loadView() {
        super.loadView()
        title = "B"
        view.backgroundColor = .white
        setColors()
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        animate()
    }

    override func willMove(toParentViewController parent: UIViewController?) { // tricky part in iOS 10
        navigationController?.navigationBar.barTintColor = .red //previous color
        super.willMove(toParentViewController: parent)
    }

    override func viewDidAppear(_ animated: Bool) {
        navigationController?.navigationBar.barTintColor = .blue
    }

    private func animate() {
        guard let coordinator = self.transitionCoordinator else {
            return
        }
        coordinator.animate(alongsideTransition: {
            [weak self] context in
            self?.setColors()
        }, completion: nil)
    }

    private func setColors(){
        navigationController?.navigationBar.tintColor = .black
        navigationController?.navigationBar.barTintColor = .blue
    }

}

UPDATE iOS 10

In the iOS 10 the tricky part is to add the willMoveTo(parentViewController parent: UIViewController?) in the second ViewController. And set the navigationBar tintColor to the color value of previous controller. Also, in viewDidAppear method in second ViewControler set the navigationBar.tintColor to the color from second viewController.

Check out my example project on github

Answer 2

You can fix this popping issue by adding something similar to this, running it in viewWillDisappear won't work for some reason in iOS10

override func willMove(toParentViewController parent: UIViewController?) {
    self.navigationController?.navigationBar.barTintColor = UIColor.red
    super.willMove(toParentViewController: parent)
}