Question

im面临着迅速设置一个ViewController标题的字体颜色并在消失时重置它的问题。目前，我可以使用以下方法将颜色设置为黑色到白色：

override func viewDidLoad() {
  let textAttributes = [NSAttributedStringKey.foregroundColor:UIColor.white]
  navigationController?.navigationBar.titleTextAttributes = textAttributes
}


override func viewWillDisappear(_ animated: Bool) {
  let textAttributes = [NSAttributedStringKey.foregroundColor:UIColor.black]
  navigationController?.navigationBar.titleTextAttributes = textAttributes
}

当我尝试使用UIColor.black进行重置时，它没有任何改变。

当我尝试设置整个外观时，根本没有任何改变。

override func viewDidLoad() {
  UINavigationBar.appearance().titleTextAttributes = [NSAttributedStringKey.foregroundColor : UIColor.white]
}


override func viewWillDisappear(_ animated: Bool) {
  UINavigationBar.appearance().titleTextAttributes = [NSAttributedStringKey.foregroundColor : UIColor.black]
}

我如何仍能实现这一目标？使用Xcode 10.0 斯威夫特4

Answer 1

不是将代码添加到JLabel，而是将其添加到viewDidLoad()，即

viewDidAppear(_:)

Answer 2

感谢大家的帮助。

我通过其他功能为它工作：

people.forEach(x -> {
        x.getLanguagesSpoken().forEach(lang -> {
            langPersons.computeIfAbsent(lang, ignoreMe -> new ArrayList<>()).add(x);
        });
});

建立视图时也会调用此函数。此解决方案对我有效，显示视图时已经设置了颜色。
我愿意接受对此的回应。

Answer 3

您可以在任何视图的代码中使用viewWillAppear函数

func navigationBarProperties(vc:UIViewController, title:String){
 vc.navigationController!.navigationBar.isHidden = false
 vc.navigationController!.navigationBar.isTranslucent = false
 // text color
 vc.navigationController!.navigationBar.tintColor = UIColor.white
 // bar color
 vc.navigationController!.navigationBar.barTintColor = UIColor.black
 let isFont = UIFont.init(name: "Helvetica-bold", size: 15)
 vc.navigationItem.title = title
 vc.navigationController!.navigationBar.titleTextAttributes = [NSAttributedStringKey.foregroundColor: #colorLiteral(red: 1, green: 1, blue: 1, alpha: 1) ,NSAttributedStringKey.font: isFont!]
}

override open func viewWillAppear(_ animated: Bool) {
 super.viewWillAppear(animated)
 //---nav bar customization----//
 navigationBarProperties(vc: self, title: "Home")
 }

Answer 4

子类UINavigationController并将其分配给您的navigationController：

class CustomNavigationController : UINavigationController {

    let usualTextAttributes: [NSAttributedString.Key: Any] = [.foregroundColor: UIColor.red]
    let customTextAttributes: [NSAttributedString.Key: Any] = [.foregroundColor: UIColor.blue]

    private func updateTitleColorIfNeeded() {
        if topViewController is MyCustomViewController {
            navigationBar.titleTextAttributes = customTextAttributes
        } else {
            navigationBar.titleTextAttributes = usualTextAttributes
        }
    }

    override func popViewController(animated: Bool) -> UIViewController? {
        updateTitleColorIfNeeded()
        return super.popViewController(animated: animated)
    }

    override func pushViewController(_ viewController: UIViewController, animated: Bool) {
        updateTitleColorIfNeeded()
        super.pushViewController(viewController, animated: animated)
    }
}

如果MyCustomViewController是导航控制器的根，请在viewDidLoad中设置其初始标题颜色：

class MyCustomViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        navigationController?.navigationBar.titleTextAttributes = [.foregroundColor: UIColor.yellow]
    }
}

NavigationBar为一个视图设置TitleColor

4 个答案: