ios - 如何更改与初始颜色不同的导航栏按钮项目颜色？

Question

我已经从 View A 导航到 View B(使用新的导航 Controller 和黑色导航栏)

查看一个 Controller :

    // With Navigation Controller
    let storyBoard: UIStoryboard = UIStoryboard(name: "ViewB", bundle: nil)
    let newViewController = storyBoard.instantiateViewController(withIdentifier: "ViewB") as! ViewBController
    let navCont = UINavigationController(rootViewController: newViewController)
    // Change the navigation bar to translucent
    navCont.navigationBar.setBackgroundImage(UIImage(), for: .default)
    navCont.navigationBar.shadowImage = UIImage()
    navCont.navigationBar.isTranslucent = true
    navCont.navigationBar.tintColor = UIColor.black
    //present(navCont, animated: true, completion: nil)
    show(navCont, sender: nil)

当从 View B 导航到 View C 时，我想将 navigationBar.tintColor 从黑色更改为白色。

View B Controller :

@IBAction func staticQRBtnPressed(_ sender: Any) {
    // Without Navigation Controller
    let storyBoard: UIStoryboard = UIStoryboard(name: "ViewC", bundle: nil)
    let newViewController = storyBoard.instantiateViewController(withIdentifier: "ViewCController") as! ViewCController
    newViewController.navigationController?.navigationBar.barTintColor = UIColor.white
    newViewController.navigationController?.navigationBar.titleTextAttributes = [.foregroundColor: UIColor.white]
    self.show(newViewController, sender: nil) // Push to navigation stack
}

查看 C Controller :

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    navigationController?.navigationBar.barTintColor = UIColor.white
    navigationController?.navigationBar.titleTextAttributes = [.foregroundColor: UIColor.white]
}

为什么上面的方法都不行？

Answer 1

除了为什么它不起作用，它不是交互式的。因此，如果用户向后滑动且未与导航动画同步，它将无法正常工作。因此，如果您想要一个有效的交互式解决方案，我们开始吧:

定义自定义颜色协议(protocol):

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

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

子类 UINavigationController 并覆盖导航方法:

/**
 UINavigationController with different colors support of UINavigationBar.
 To use it please adopt needed child view controllers to protocol `NavigationBarColorable`.
 - note: Don't forget to set initial tint and barTint colors
 */
class AppNavigationController: UINavigationController {    

    override func viewDidLoad() {
        super.viewDidLoad()
        navigationBar.setBackgroundImage(UIImage(), for: .any, barMetrics: .default)
        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)
        }

        setTabBarHidden(viewController is TabBarHidable)

        super.pushViewController(viewController, animated: animated)
    }

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

        setTabBarHidden(previousViewController is TabBarHidable)

        // 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 }
            self.setTabBarHidden(self.topViewController is TabBarHidable)
            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,
                .font : R.font.iranSansFaNumBold(size: 14)!
            ]
            navigationBar.tintColor = tintColor
        }

        navigationBar.barTintColor = colors.navigationBarTintColor
    }
}

并在每个你想要自定义导航颜色的 View Controller 中遵循和实现协议(protocol)方法:

extension MyCustomViewController: NavigationBarColorable {
    public var navigationBarTintColor: UIColor? { return .red }
    public var navigationTintColor: UIColor? { return .blue }
}

注意 1:我添加了文本颜色更改支持。

注意 2:我使用了我的一个项目代码作为这个答案的基础，如果您看到一些非通用的命名等，我们深表歉意。

注意 3:正如我在代码中提到的，不要忘记设置初始色调和 barTint 颜色。