How can I unwind to the MainView in SwiftUI

Question

I can't find a way to go to the ContentView from ViewB without showing a secound NavigationView on top of the other NavigationView.

struct ContentView: View {
    var body: some View {
        NavigationView{
            VStack {
                Text("Go to ViewA")
                NavigationLink(destination: ViewA()) {Text("Go")}
            }.navigationBarTitle("ContentView")
        }
    }
}

struct ViewA: View {
   @Environment(\.presentationMode) var presentationMode
    var body: some View {
        VStack {
            Text("Go to ViewB")
            NavigationLink(destination: ViewB()) {Text("Go to B")}
            Text("Go back")
            Button(action: { self.presentationMode.wrappedValue.dismiss() }) {Text("Go to ContentView")}
        }.navigationBarTitle("ViewA")
    }
}

struct ViewB: View {
    @Environment(\.presentationMode) var presentationMode
    var body: some View {
        VStack {
            Text("Go Home")
            NavigationLink(destination: ContentView()) {Text("Go")}
            Text("Go back")
            Button(action: { self.presentationMode.wrappedValue.dismiss() }) {Text("Go to ViewB")}
        }.navigationBarTitle("ViewB")
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

In the "old" Swift i could easily make an unwindSegue like

@IBAction func unwindToVCMain(segue:UIStoryboardSegue) { }
}

and easily call it like

performSegue(withIdentifier: "unwindToVcMain", sender: nil)

Answer 1

Using the Swiftui NavigationLink

First, embed your first view in a navigation controller.

Then you insert a navigation link to the next view. The NavigationLink has different initialisers. Choose this one with the isActive parameter:

It is a bit mind-bending at first, but the isActive parameter in the NavigationLink becomes true when the link is clicked and the navigation moves to the next screen.

It creates an instance that presents a destination when active

If I pass a binding keeping track of the state of this property, if at any time in my subsequent chain of views I set it to false again, it will reset and return to the original screen! It is quite neat!!

See this short example in code:

struct ContentView: View {
    @State private var isActive: Bool = false

    var body: some View {
        NavigationView {
            NavigationLink(
                destination: SecondView(isActive: $isActive),
                isActive: $isActive,
                label: {
                    Text("Go to second View")
                })
                .navigationTitle("MainView")
        }
    }
}

My second View:

struct SecondView: View {
    @Binding var isActive: Bool

    var body: some View {
            NavigationLink("Go to Third View",destination:  ThirdView(isActive: $isActive))
                .navigationTitle("Second View")
    }
}

And here the button to unwind, but it could be in any view. Setting isActive = false does some magic here!

struct ThirdView: View {
    @Binding var isActive: Bool

    var body: some View {
        Button("Unwind!"){
            isActive = false
        }
        .navigationTitle("Last View!")
    }
}