SwiftUI Toggle how to distinguish changing value by UI action vs changing programatically

Question

If i have a toggle, which updates its state from external async load but also by user intput, how can i differentiate those two? eg. to perform a special action on user action

    Group {
        Toggle(isOn: $on) {
            EmptyView()
        }
    }
    .onChange(of: on) { newValue in
        was "on" changed by user or onAppear async update?
    }
    .onAppear {
        async update on
    }

PS: this is mostly for macOS, and there the tapGesture on Toggle doesn't work

Answer 1

If you want a side effect for use the user actions, you can use a custom wrapper Binding:

struct ContentView: View {
    @State private var on: Bool = false
    
    var userManagedOn: Binding<Bool> {
        .init {
            return on
        } set: { newValue in
            print("Side effect")
            on = newValue
        }
    }
    
    var body: some View {
        VStack {
            Group {
                Toggle(isOn: userManagedOn) {
                    EmptyView()
                }
            }
        }
        .padding()
        .onAppear {
            Task { @MainActor in
                try? await Task.sleep(nanoseconds: NSEC_PER_SEC)
                on.toggle()
            }
        }
    }
}