.swift

var body: some View {
        NavigationView {
            VStack {
                
                // get the selected customer
                CustomerListView(customers: customers) { (customer) in
                    selectedCustomer = customer
                }
                
                if let selectedCustomer = selectedCustomer {
                    NavigationLink(
                        destination: DetailView(customer: selectedCustomer),
                        isActive: .constant(true)) {
                        EmptyView()
                    }
                }
            }
            .onAppear {
                 selectedCustomer = nil
            }
            
            .navigationTitle("Customers")
        }
        
    }