How to 'intercept' NavigationLink push?

[CamilleScholtz]

I am using a NavigationSplitView, where the buttons in the sidebar are NavigationLinks. I can't really use anything else as seemingly only NavigationLink does things like coloring the background of the active category. There is however a problem, because NavigationLink always pushes, it seems that this means it also bypasses things like .onNavigationReceive.

A quick illustration of the code I have with the question being, how can I make this actually work.

NavigationSplitView {
    SidebarView(selectedDestination: $selectedDestination)
        .navigationSplitViewColumnWidth(180)
} content: {
    ManagedNavigationStack(name: "content") {
        selectedDestination
            .navigationDestination(Destination.self)
    }
    .navigationSplitViewColumnWidth(310)
    .navigationBarBackButtonHidden(true)
    .ignoresSafeArea()
    .overlay(
        LoadingView(selectedDestination: $selectedDestination)
    )
} detail: {
    ViewThatFits {
        DetailView()
    }
    .padding(60)
}
.onNavigationReceive { (destination: Destination) in
    switch destination {
    case .albums, .artists, .songs:
        guard mpd.status.playlist != nil else {
            selectedDestination = destination

            return .immediately
        }
    case let .playlist(playlist):
        guard playlist != mpd.status.playlist else {
            selectedDestination = destination

            return .immediately
        }
    default:
        return .immediately
    }

    navigator.perform(
        .reset,
        .playlistChangeRequired,
        .send(destination)
    )

    return .auto
}

struct SidebarView: View {
    @Environment(MPD.self) private var mpd
    @Environment(\.navigator) private var navigator: Navigator

    @Binding var selectedDestination: Destination?

    var body: some View {
        List(selection: $selectedDestination) {
            ForEach(Destination.categories) { category in
                // Never reaches the above `onNavigationReceive`
                NavigationLink(value: category) {
                    Label(category.label!, systemSymbol: category.symbol)
                }
                
                // Reaches `onNavigationReceive`, but no active category styling
                Label(category.label!, systemSymbol: category.symbol)
                    .onTapGesture {
                        navigator.navigate(to: category)
                    }
            }
        }

[hmlongco]

The first problem is a misunderstanding of onNavigationReceive and its intended purpose. it's not a general-purpose "onNavigation" notification handler. Its sole purpose is to receive values sent by navigator.send, usually in response to a deep linking or internal navigation event.

Second, and as mentioned in the documentation, NavigationLink(value:) will always push. That's its job. (A job reinforced, I might add, by the chevrons and visual indicators added when using it.)

[CamilleScholtz]

Okay, thanks for the quick response! Maybe instead of showing my botched solution, telling what I actually want might be easier.

• I have a sidebar with some destinations; .albums, .songs, .artists and zero or more .playlist(Playlist)
• These buttons control what is displayed in the content section of the NavigationSplitView
• Whenever an user switches these destinations, I want my program to check if its loaded playlist matches a corresponding value
• if this is not the case I want to display an .alert() warning the user that this will overwrite the current playlist. The user can continue or cancel. This is playlistChangeRequired in the above code.

How would I go about doing that?

[hmlongco]

Getting outside the scope of Navigator. The classic NavigationSplitView uses a binding to show the content view. You'd need some code to do the check and then do the right thing. You can't use NavigationLink(value:) (or any NavigationLink, for that matter) as it will always push and that push can't be cancelled.

[CamilleScholtz]

Alright, thanks