Question

我正在寻找一种更改状态栏的 text 颜色的方法，该颜色允许为每个视图使用不同的文本颜色。

我见过this Q&A，但这不是我想要的。我不是在寻找只允许所有视图使用一种状态栏文本颜色的解决方案。我想为每个视图更改状态栏文本颜色。例如，一个视图可能具有深色背景，因此我需要浅色文本。我可能会导航到具有浅色背景的其他视图，因此现在我需要深色文本。建议的重复答案仅返回.lightContent ，这意味着当我移至其他视图时，状态栏文本颜色无法动态更改。

This answer here可在我的计算机上运行，但性能不佳。它下面的评论证实了这一点。滞后是不可接受的，因此此解决方案不好。

到目前为止，我看到的其他解决方案会导致此特定错误：

Compiling failed: extensions of generic classes cannot contain '@objc' members

我还尝试在自定义控制器中使用环境对象：

import SwiftUI /// Allows for the status bar colors to be changed from black to white on the dark gray title bar class Controller<ContentView> : UIHostingController<ContentView> where ContentView : View { @EnvironmentObject var statusBarTextColor: StatusBarTextColor lazy var isDark: Bool = self.statusBarTextColor.isDark override var preferredStatusBarStyle: UIStatusBarStyle { return isDark ? .lightContent : .darkContent } }

这会导致错误：

Thread 1: Fatal error: No ObservableObject of type StatusBarTextColor found. A View.environmentObject(_:) for StatusBarTextColor may be missing as an ancestor of this view.

在我的SceneDelegate文件中，我确实指定了StatusBarTextColor环境对象：

window.rootViewController = Controller( rootView: Home() .environmentObject(PostData()) .environmentObject(CardPosition()) .environmentObject(StatusBarTextColor()) )

这是ObservableObject本身：

import Combine import SwiftUI final class StatusBarTextColor: ObservableObject { @Published var isDark: Bool = true }

如果我想知道为什么这行不通，那是因为Controller在StatusBarTextColor可用之前被初始化了。

我对这个问题的研究越多，我就认为没有办法解决。我几乎阅读了有关该主题的每篇文章，答案和视频。他们都使用Controller仅返回.lightContent，或者使用情节提要和多个控制器，这不是我正在使用的。

Answer 1

您可以使用您找到的解决方案 here，但您可以创建一个名为 onWillDisappear 的视图修饰符来公开 viewWillDisappear，而不是使用 onDisappear，这会延迟颜色更改直到视图完全消失。颜色变化会尽快发生。

用法：

struct MyClass: View {
      @Environment(\.localStatusBarStyle) var statusBarStyle
    // ...
        SomeView()
        }.onAppear {
            self.statusBarStyle.currentStyle = .darkContent
        }
        .onWillDisappear {
            self.statusBarStyle.currentStyle = .lightContent
        }
}

代码：

   import SwiftUI
    
    
    class HostingController<Content>: UIHostingController<Content> where Content: View {
        private var internalStyle = UIStatusBarStyle.lightContent
    
        @objc override dynamic open var preferredStatusBarStyle: UIStatusBarStyle {
            get {
                internalStyle
            }
            set {
                internalStyle = newValue
                self.setNeedsStatusBarAppearanceUpdate()
            }
        }
    
        override init(rootView: Content) {
            super.init(rootView:rootView)
    
            LocalStatusBarStyleKey.defaultValue.getter = { self.preferredStatusBarStyle }
            LocalStatusBarStyleKey.defaultValue.setter = { self.preferredStatusBarStyle = $0 }
        }
    
        @objc required dynamic init?(coder aDecoder: NSCoder) {
            super.init(coder: aDecoder)
        }
    }
    
    class LocalStatusBarStyle { // style proxy to be stored in Environment
        fileprivate var getter: () -> UIStatusBarStyle = { .default }
        fileprivate var setter: (UIStatusBarStyle) -> Void = {_ in}
    
        var currentStyle: UIStatusBarStyle {
            get { self.getter() }
            set { self.setter(newValue) }
        }
    }
    
    // Custom Environment key, as it is set once, it can be accessed from anywhere
    // of SwiftUI view hierarchy

struct LocalStatusBarStyleKey: EnvironmentKey {
    static let defaultValue: LocalStatusBarStyle = LocalStatusBarStyle()
}

extension EnvironmentValues { // Environment key path variable
    var localStatusBarStyle: LocalStatusBarStyle {
        get {
            return self[LocalStatusBarStyleKey.self]
        }
    }
}

struct WillDisappearHandler: UIViewControllerRepresentable {
    func makeCoordinator() -> WillDisappearHandler.Coordinator {
        Coordinator(onWillDisappear: onWillDisappear)
    }

    let onWillDisappear: () -> Void

    func makeUIViewController(context: UIViewControllerRepresentableContext<WillDisappearHandler>) -> UIViewController {
        context.coordinator
    }

    func updateUIViewController(_ uiViewController: UIViewController, context: UIViewControllerRepresentableContext<WillDisappearHandler>) {
    }

    typealias UIViewControllerType = UIViewController

class Coordinator: UIViewController {
        let onWillDisappear: () -> Void

        init(onWillDisappear: @escaping () -> Void) {
            self.onWillDisappear = onWillDisappear
            super.init(nibName: nil, bundle: nil)
        }

        required init?(coder: NSCoder) {
            fatalError("init(coder:) has not been implemented")
        }

        override func viewWillDisappear(_ animated: Bool) {
            super.viewWillDisappear(animated)
            onWillDisappear()
        }
    }
}
struct WillDisappearModifier: ViewModifier {
    let callback: () -> Void

    func body(content: Content) -> some View {
        content
            .background(WillDisappearHandler(onWillDisappear: callback))
    }
}

extension View {
    func onWillDisappear(_ perform: @escaping () -> Void) -> some View {
        self.modifier(WillDisappearModifier(callback: perform))
    }
}

查看带有 onWillDisappear 代码 here

的原始帖子

Answer 2

在您的SceneDelegate中，将StatusBarTextColor()注入到Home视图中。但是，您在Controller中声明了EvironmentObject。

如何在SwiftUI中更改每个视图的状态栏文本颜色？

2 个答案: