objectWillChange do not update view - ios

Question

I have ViewModel which looks like this:
class ItemsListViewModel : ObservableObject{
var response : ItemsListResponse? = nil
var itemsList : [ListItem] = []
var isLoading = true
let objectWillChange = PassthroughSubject<Void, Never>()
func getItems() {
self.isLoading = true
ApiManager.shared.getItems()
.sink(receiveCompletion: {completion in
}, receiveValue: {
self.response = data
self.isLoading = false
self.objectWillChange.send()
})
}
}
When I receive data from network request I use self.objectWillChange.send() to notify view, but view do not react to this.
My views :
ItemsView
struct ItemsView: View {
var body: some View {
VStack{
Text("Some Title")
ItemsListView()
}
}
}
ItemsListView
struct ItemsListView: View {
#ObservedObject var myViewModel = ItemsListViewModel()
var body: some View {
VStack{
Text("\(self.myViewModel.response?.total")
}.onAppear{
self.myViewModel.getItems()
}
}
}
But the interesting thing, that if I use ItemsListView not inside
ItemsView everything works perfectly. How can i solve this problem?

Answer 1

try this ( i simplified just your model to test in playground)
you can copy directly the code in playground and check
struct Model {
var items : [String]
}
class ItemsListViewModel : ObservableObject {
#Published var items : [String] = ["Test 1", "Test2"]
}
let myViewModel = ItemsListViewModel()
struct ItemsView: View {
var body: some View {
VStack{
Text("Some Title")
ItemsListView().environmentObject(myViewModel)
}
}
}
struct ItemsListView: View {
#EnvironmentObject private var model : ItemsListViewModel
var body: some View {
VStack{
Text("\(model.items.count)")
}
}
}
struct ContentView: View {
var body: some View {
ItemsView()
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView().environmentObject(myViewModel)
}
}

Answer 2

Using #Published for properties of ObservableObject does fix your issue. See simplified below demo:
import SwiftUI
import Combine
class ItemsListViewModel : ObservableObject{
#Published var response = ""
var isLoading = true
func getData() {
self.isLoading = true
DispatchQueue.main.async {
Just("test")
.sink(receiveCompletion: {completion in
}, receiveValue: { data in
self.response = data
self.isLoading = false
})
}
}
}
struct ItemsListView: View {
#ObservedObject var myViewModel = ItemsListViewModel()
var body: some View {
VStack{
Text("\(self.myViewModel.response)")
}.onAppear{
self.myViewModel.getData()
}
}
}
struct ItemsView: View {
var body: some View {
VStack{
Text("Some Title")
ItemsListView()
}
}
}
struct TestPublished: View {
var body: some View {
ItemsView()
}
}
struct TestPublished_Previews: PreviewProvider {
static var previews: some View {
TestPublished()
}
}