struct DetailView: View {
   @Binding var viewPath: NavigationPath
   var book: Book

   var body: some View {
      VStack {
         Text(book.title)
            .font(.title)
         Text(book.author)
         Image(book.cover)
            .resizable()
            .scaledToFit()
            .frame(width: 100)
         Spacer()
      }.padding()
      .navigationTitle(Text("Book"))
      .navigationBarBackButtonHidden(true)
      .toolbar {
         ToolbarItem(placement: .topBarLeading) {
            Button("Back") {
               viewPath.removeLast()
            }
         }
      }
   }
}
#Preview {
   @Previewable @State var navigation = NavigationPath()

   NavigationStack {
      DetailView(viewPath: $navigation, book: ApplicationData.shared.userData[0])
   }
}