SwiftUI hiding a navigation bar only when looking at ContentView

问题

I have a Content file and am hiding the navigation bar because it takes up space and pushes elements down. One of the buttons in the ContentView redirects (using a navigation link) to another view. In this other view, the navigationBar is still hidden....for simplicity sake, I'll cut out some of the code from ContentView:

//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)
        }
    }
}

Also...there may have been typos because I just copied the code over from another computer. Sorry and thank you in advance!

回答1:

Firstly, you don't need to have this isPresentedSettings variable for presenting a NavigationLink.

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

And there should be only one NavigationView in your view hierarchy.

This is how your final code can look like:

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
        }
    }
}

来源：https://stackoverflow.com/questions/62183775/swiftui-hiding-a-navigation-bar-only-when-looking-at-contentview

标签

swift

swiftui

navigationbar

navigationview