SwiftUI 仅在查看 ContentView 时隐藏导航栏

Question

我有一个内容文件并隐藏导航栏，因为它占用空间并将元素向下推。 ContentView 中的一个按钮重定向（使用导航链接）到另一个视图。在另一个视图中，navigationBar 仍然是隐藏的……为简单起见，我将从 ContentView 中删除一些代码：

//this is the view that looks "fine" (i.e. the navigation bar takes up no space)
struct ContentView: View {
    @State private var isPresentedSettings = false
    var body: some View {
        NavigationView {
            ZStack {
                VStack {
                    SettingsButton(isPresentedSettings: $isPresentedSettings)
                }
            }.navigationBarTitle("").navigationBarHidden(true)
        }
    }
}

//this is the button that pulls up the settings page view
struct SettingsButton: View {
    @Binding var isPresentedSettings: Bool
    var body: some View {
        NavigationLink (destination: SettingsPageView(isPresentedSettings: 
        self.$isPresentedSettings)) {
            Button(action: { self.isPresentedSettings.toggle() }, label: { Text("Button") })
        }
    }
}

//This is the view that should have a navigationbar but it doesn't
struct SettingsPageView: View {
    @Binding var isPresentedSettings: Bool
    var body: some View {
        NavigationView {
            VStack {
                Text("This is a view")
            }.navigationBarTitle("Settings", displayMode: .inline)
        }
    }
}

另外...可能有错别字，因为我刚刚从另一台计算机复制代码。抱歉，提前谢谢您！

Answer 1

首先，您不需要有这个isPresentedSettings 变量来呈现NavigationLink。

NavigationLink(destination: SettingsPageView()) {
    Text("Button")
}

您的视图层次结构中应该只有一个NavigationView。

这就是你的最终代码的样子：

struct ContentView: View {
    @State private var navBarHidden = true

    var body: some View {
        NavigationView {
            ZStack {
                VStack {
                    SettingsButton(navBarHidden: $navBarHidden)
                }
            }
            .navigationBarHidden(navBarHidden)
        }
    }
}

struct SettingsButton: View {
    @Binding var navBarHidden: Bool

    var body: some View {
        NavigationLink(destination: SettingsPageView(navBarHidden: $navBarHidden)) {
            Text("Show View")
        }
    }
}

struct SettingsPageView: View {
    @Binding var navBarHidden: Bool

    var body: some View {
        VStack {
            Text("This is a view")
        }
        .navigationBarTitle("Settings", displayMode: .inline)
        .onAppear {
            self.navBarHidden = false
        }
        .onDisappear {
            self.navBarHidden = true
        }
    }
}