SwiftUI: .listRowBackground is not updated when new item added to the List

Question

I'm trying to find the reason why .listRowBackground is not updated when a new item has been added to the list. Here is my code sample:

   @main
    struct BGtestApp: App {
    
        @ObservedObject var viewModel = ViewModel()
    
        var body: some Scene {
            WindowGroup {
                ContentView()
                    .environmentObject(viewModel)
            }
        }
    }

struct ContentView: View {

    @EnvironmentObject var vm: ViewModel
    
    var body: some View {
        NavigationView {
            List {
                ForEach(vm.items, id: \.self) { item in
                    NavigationLink {
                        DetailView().environmentObject(vm)
                    } label: {
                        Text(item)
                    }
                    .listRowBackground(Color.yellow)
                }
            }
        }
    }
}

struct DetailView: View {

    @EnvironmentObject var vm: ViewModel

    var body: some View {
        Button("Add new") {
            vm.items.append("Ananas")
        }
    }
}

How it looks like:

TIA for you help!

Answer 1

You can force the list to refresh when you cone back to the list. You can tag an id for your list by using .id(). Here is my solution:

struct ContentView: View {
    @EnvironmentObject var vm: ViewModel
    @State private var viewID = UUID()
    
    var body: some View {
        NavigationView {
            List {
                ForEach(vm.items, id: \.self) { item in
                    NavigationLink {
                        DetailView()
                            .environmentObject(vm)
                    } label: {
                        Text(item)
                    }
                }
                .listRowBackground(Color.yellow)
            }
            .id(viewID)
            .onAppear {
                viewID = UUID()
            }
        }
    }
}

Hope it's helpful for you.

Answer 2

The solution I found is not ideal, but should work. What I did is made items to be @State variable :

struct ContentView: View {

    @EnvironmentObject var vm: ViewModel

    @State var items: [String] = []

    var body: some View {
        NavigationView {
            VStack {
                List {
                    ForEach(items, id: \.self) { item in
                        NavigationLink {
                            DetailView().environmentObject(vm)
                        } label: {
                            RowView(item: item)
                        }
                        .listRowBackground(Color.yellow)
                    }
                }
                .onAppear {
                    self.items = vm.items
                }
            }
        }