Question

我已升级到XCode 8.0 / iOS 10，现在我的导航栏的颜色更改动画不再有效，它直接更改颜色而没有任何动画。

UIView.animateWithDuration(0.2, animations: {
    self.navigationController?.navigationBar.barTintColor = currentSection.color!
})

任何人都知道如何解决这个问题？

Answer 1

要在iOS10中为navigationBar的颜色变化设置动画，您需要在动画块中设置颜色后调用layoutIfNeeded。

示例代码：

UIView.animateWithDuration(0.5) { 
    self.navigationController?.navigationBar.barTintColor = UIColor.redColor()
    self.navigationController?.navigationBar.layoutIfNeeded()
}

另外，我想在barTintColor这样的属性中告知Apple doesn’t officialy support动画，以便该方法可以随时中断。

如果在动画期间在导航栏上调用-layoutIfNeeded 阻止它应该更新它的背景属性，但考虑到性质这些属性做了什么，真的没有任何一种保证你可以动画其中任何一个。

Answer 2

互动动画

定义协议：

/// Navigation bar colors for `ColorableNavigationController`, called on `push` & `pop` actions
public protocol NavigationBarColorable: UIViewController {
    var navigationTintColor: UIColor? { get }
    var navigationBarTintColor: UIColor? { get }
}

public extension NavigationBarColorable {
    var navigationTintColor: UIColor? { return nil }
}

定义自定义NavigationController子类：

class AppNavigationController: UINavigationController {

    override func viewDidLoad() {
        super.viewDidLoad()
        navigationBar.shadowImage = UIImage()
        if let colors = rootViewController as? NavigationBarColorable {
            setNavigationBarColors(colors)            
        }
    }

    private var previousViewController: UIViewController? {
        guard viewControllers.count > 1 else {
            return nil
        }
        return viewControllers[viewControllers.count - 2]
    }

    override open func pushViewController(_ viewController: UIViewController, animated: Bool) {
        if let colors = viewController as? NavigationBarColorable {
            setNavigationBarColors(colors)
        }

        super.pushViewController(viewController, animated: animated)
    }

    override open func popViewController(animated: Bool) -> UIViewController? {
        if let colors = previousViewController as? NavigationBarColorable {
            setNavigationBarColors(colors)
        }

        // Let's start pop action or we can't get transitionCoordinator()
        let popViewController = super.popViewController(animated: animated)

        // Secure situation if user cancelled transition
        transitionCoordinator?.animate(alongsideTransition: nil, completion: { [weak self] context in
            guard let `self` = self else { return }

            guard let colors = self.topViewController as? NavigationBarColorable else { return }
            self.setNavigationBarColors(colors)
        })

        return popViewController
    }

    override func popToRootViewController(animated: Bool) -> [UIViewController]? {
        if let colors = rootViewController as? NavigationBarColorable {
            setNavigationBarColors(colors)
        }

        let controllers = super.popToRootViewController(animated: animated)

        return controllers
    }

    private func setNavigationBarColors(_ colors: NavigationBarColorable) {

        if let tintColor = colors.navigationTintColor {
            navigationBar.titleTextAttributes = [
                .foregroundColor : tintColor
            ]
            navigationBar.tintColor = tintColor
        }

        navigationBar.barTintColor = colors.navigationBarTintColor
    }
}

现在，您可以在NavigationBarColorable内部的任何控制器中遵守AppNavigationController，并为其提供所需的任何颜色。

extension FirstViewController: NavigationBarColorable {
    public var navigationBarTintColor: UIColor? { UIColor.red }
    public var navigationTintColor: UIColor? { UIColor.white }
}

extension SecondViewController: NavigationBarColorable {
    public var navigationBarTintColor: UIColor? { UIColor.blue }
    public var navigationTintColor: UIColor? { UIColor.orange }
}

别忘了实现此有用的扩展：

extension UINavigationController {
    var rootViewController: UIViewController? {
        return viewControllers.first
    }
}

iOS10中的动画导航栏barTintColor更改无法正常工作

2 个答案:

互动动画