import SwiftUI

struct Detail: View {
  let text: String
  var body: some View { Text(text).navigationTitle("Detail") }
}

struct NavStackDemo: View {
  var body: some View {
    NavigationStack {
      List(1...3, id: \.self) { i in
        NavigationLink("Item \\ (i)", destination: Detail(text: "Item \\ (i)"))
      }
      .navigationTitle("Items")
      .toolbar { ToolbarItem(placement: .navigationBarTrailing) { Button("Add") {} } }
    }
  }
}

                    

import SwiftUI

struct ContentView: View {
  var body: some View {
    NavStackDemo()
  }
}

                    

import SwiftUI

@main
struct MyApp: App {
  var body: some Scene {
    WindowGroup { ContentView() }
  }
}