SwiftUI update data for parent NavigationView - data-binding

Question

how can I update data in TextField that lives in the detail of a NavigationView? I want the data to be updated in the List of the parent View. Here is my code:
class Address: ObservableObject, Identifiable {
let id = UUID()
#Published var name: String
#Published var age: String
init(name: String, age: String) {
self.name = name
self.age = age
}
}
class AddressBook: ObservableObject {
#Published var addresses: [Address]
init(addresses: [Address]) {
self.addresses = addresses
}
}
struct TestData {
static let addressbook = AddressBook(addresses: [
Address(name: "Person1", age: "39"),
Address(name: "Person2", age: "22")
])
}
struct ContentView: View {
#ObservedObject var addressbook = TestData.addressbook
var body: some View {
NavigationView {
List (addressbook.addresses) {address in
NavigationLink(destination: AddressDetail(address: address)) {
Text(address.name)
}
}
.navigationBarTitle("Addressbook")
}
}
}
struct AddressDetail: View {
#ObservedObject var address: Address
var body: some View {
Form {
TextField("name", text: $address.name)
TextField("age", text: $address.age)
}
}
}
This code doesn't work: If I go to the AddressDetail-View, change the TextField values and then go back, the changes don't update in the List-View.
Nico

Answer 1

The problem is that Address is a class, so if its published properties changed the reference in addresses is not changed, but ContentView view observes addressbook as a container of addresses.
Here is demo of possible approach (tested & works with Xcode 12b / iOS 14, also on 11.4 / iOS 13.4)
List (addressbook.addresses) {address in
NavigationLink(destination: AddressDetail(address: address)) {
Text(address.name)
.onReceive(address.objectWillChange) { _ in
self.addressbook.objectWillChange.send()
}
}
}
Alternate: based on Binding (requires much more changes, so, as for me, less preferable, but worth mention
struct Address: Identifiable, Hashable {
let id = UUID()
var name: String
var age: String
init(name: String, age: String) {
self.name = name
self.age = age
}
}
class AddressBook: ObservableObject {
#Published var addresses: [Address]
init(addresses: [Address]) {
self.addresses = addresses
}
}
struct TestData {
static let addressbook = AddressBook(addresses: [
Address(name: "Person1", age: "39"),
Address(name: "Person2", age: "22")
])
}
struct ContentView: View {
#ObservedObject var addressbook = TestData.addressbook
var body: some View {
NavigationView {
List (Array(addressbook.addresses.enumerated()), id: \.element) { i, address in
NavigationLink(destination: AddressDetail(address: self.$addressbook.addresses[i])) {
Text(address.name)
}
}
.navigationBarTitle("Addressbook")
}
}
}
struct AddressDetail: View {
#Binding var address: Address
#State private var name: String
#State private var age: String
init(address: Binding<Address>) {
_address = address
_name = State(initialValue: _address.wrappedValue.name)
_age = State(initialValue: _address.wrappedValue.age)
}
var body: some View {
Form {
TextField("name", text: $name)
TextField("age", text: $age)
}
.onDisappear {
self.address.name = self.name
self.address.age = self.age
}
}
}