iOS 10 barTintColor 动画

Question

我注意到 ios 10 中条形颜色动画的方式发生了变化。我创建了一个示例项目来概述更改：Github: ios10BarTintDemo

基本上在 ios 9 上，barTintColor 使用 [UIViewControllerTransitionCoordinator animateAlongsideTransition] 平滑动画

但在 ios 10 上，动画不太流畅，并且在弹出视图控制器时根本没有动画，我尝试添加 [self.navigationController.navigationBar layoutIfNeeded]，如一些类似答案中所述，但这似乎没有任何效果推/弹出控制器时。

Answer 1

更新

我在 iOS 10.3 中进行了测试，我认为问题已得到解决。 transitionCordinator 不再需要。我觉得动画很流畅。请查看我的project on github 或查看此代码：

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
    }
}

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

要实现这种动画，你应该使用UIViewControllerTransitionCoordinator as Apple documentation 说它是：

采用 UIViewControllerTransitionCoordinator 协议的对象为与视图控制器转换关联的动画提供支持。(...)

所以每个UIViewController 都有自己的transitionController。要得到这个，你应该打电话给UIViewControllerClass：

self.transitionCoordinator()

来自documentation：

返回活动转换协调器对象。

所以要得到你想要的结果，你应该在 viewController transitionCoordinatior 中实现animateAlongsideTransition 方法。当您单击backButton 并向后滑动时，动画会起作用。

例子：

第一个控制器：

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
    }
}

第二控制器：

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
    }

}

更新 iOS 10

在 iOS 10 中，棘手的部分是在 second ViewController 中添加 willMoveTo(parentViewController parent: UIViewController?)。并将 navigationBar tintColor 设置为 previous 控制器的颜色值。此外，在 second ViewControler 中的 viewDidAppear 方法中，将 navigationBar.tintColor 设置为来自 second viewController 的颜色。

看看我的例子project on github

Answer 2

您可以通过添加与此类似的内容来解决此弹出问题，在 iOS10 中由于某种原因在 viewWillDisappear 中运行它将不起作用

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