SwiftUI: How to detect navigation … | Apple Developer Forums

SwiftUI: How to detect navigation up or down

I have following SwiftUI code, which makes a connection (to the server) when the user navigates to this page (this is a part of navigation stack), and disconnects when the user navigate away (up).

Code Block struct ServiceView: View {
    @ObservedObject var state:ServiceState
    var body: some View {
        ScrollView(.vertical) {
            VStack {
            ...
                NavigationLink(
                        destination: ChildPage(state: state),
                        label: {
                            Text("Child Page")
                        })
            }
        }
        .onAppear() {
            state.connection.connect()
        }
        .onDisappear() {
            state.connection.disconnect()
        }
    }
}

Code Block
struct ServiceView: View {
@ObservedObject var state:ServiceState
var body: some View {
ScrollView(.vertical) {
VStack {
...
NavigationLink(
destination: ChildPage(state: state),
label: {
Text("Child Page")
})
}
}
.onAppear() {
state.connection.connect()
}
.onDisappear() {
state.connection.disconnect()
}
}
}

This works fine as long as the user stays on this page, but breaks when the user clicks the "Child Page" link, because .onDisappear() event will be triggered when the user navigates down as well.
Is there any way to distinguish two different scenarios (navigate up and down)?