ModalDetail.swift

import PlaygroundSupport
import SwiftUI

struct LiveView: View {
  @State var isPresented = false
  
  var modalPresentation: some View {
    NavigationView {
      Text("Hello World")
        .font(.caption)
        .navigationBarTitle(Text("Modal Contents"))
        .navigationBarItems(trailing: Button(action: { self.isPresented = false } ) { Text("Done") })
    }
  }
  
  var body: some View {
    NavigationView {
      NavigationButton(destination: Text("Hello World")
        .font(.caption)
        .navigationBarTitle(Text("Detail View Contents"))
      ) {
        Text("Show Detail View")
        }
        .navigationBarTitle(Text("Welcome"))
        .navigationBarItems(trailing:
          Button(action: { self.isPresented = true }) { Text("Show Modal") })
      }
      .presentation( isPresented ? Modal(modalPresentation, onDismiss: { self.isPresented.toggle() }) : nil )
  }
}

let liveView = LiveView()
PlaygroundPage.current.liveView = UIHostingController(rootView: liveView)