SwiftUI NavigationSplitView - Nested List Not Animating

Question

I've encountered a SwiftUI NavigationSplitView bug in my app that I'd appreciate help with, I've spent quite some time trying to work out a solution to this problem. I have a main list, which has either a Location or LocationGroup. When selecting a Location, the detail view is presented. When selecting a LocationGroup, a subsequent list of Locations are presented (from the group). When tapping on any of these Locations, the NavigationStack does not animate (push the view), and when tapping back from it, it jumps to the main selection.

I'd greatly appreciate help with this bug in my code, thanks!

Here's a GIF of the bug occurring:

I created the following sample code that reproduces the issue:

`ContentView.swift`

public enum LocationSplitViewNavigationItem: Identifiable, Hashable {
    case location(Location)
    case locationGroup(LocationGroup)

    public var id: UUID? {
        switch self {
        case .location(let location):
            return location.id
        case .locationGroup(let locationGroup):
            return locationGroup.id
        }
    }
}

struct ContentView: View {
    
    @State private var columnVisibility = NavigationSplitViewVisibility.doubleColumn
    @State private var selectedNavigationItem: LocationSplitViewNavigationItem?
    
    var body: some View {
        NavigationSplitView(columnVisibility: $columnVisibility) {
            LocationListView(selectedItem: $selectedNavigationItem, locationData: LocationSampleData(locations: LocationSampleData.sampleLocations, locationGroups: LocationSampleData.sampleLocationGroups))
        } detail: {
            if let selectedLocation = selectedNavigationItem {
                switch selectedLocation {
                case .location(let location):
                    LocationDetailView(selectedLocation: location)
                case .locationGroup(let locationGroup):
                    LocationListView(selectedItem: $selectedNavigationItem, locationData: LocationSampleData(locations: locationGroup.locations))
                }
            }
        }
        .navigationSplitViewStyle(.balanced)
    }
}

`LocationListView.swift`

struct LocationListView: View {
    
    @Binding public var selectedItem: LocationSplitViewNavigationItem?
    var locationData: LocationSampleData
    
    var body: some View {
        List(selection: $selectedItem) {
            if let locations = locationData.locations {
                ForEach(locations) { location in
                    NavigationLink(value: LocationSplitViewNavigationItem.location(location)) {
                        Text(location.name)
                            .bold()
                    }
                }
            }
            
            if let locationGroups = locationData.locationGroups {
                ForEach(locationGroups) { locationGroup in
                    NavigationLink(value: LocationSplitViewNavigationItem.locationGroup(locationGroup)) {
                        Text(locationGroup.name)
                            .bold()
                            .foregroundStyle(.red)
                    }
                }
            }
        }
        .navigationTitle("Saturday Spots")
        .navigationBarTitleDisplayMode(.large)
    }
}

`LocationDetailView.swift`

struct LocationDetailView: View {
    var selectedLocation: Location
    var body: some View {
        Text(selectedLocation.name)
            .font(.largeTitle)
            .bold()
            .foregroundStyle(LinearGradient(
                colors: [.teal, .indigo],
                startPoint: .top,
                endPoint: .bottom
            ))
            .toolbarBackground(
                Color.orange,
                for: .navigationBar
            )
            .toolbarBackground(.visible, for: .navigationBar)
    }
}

`Location.swift`

import CoreLocation

struct LocationSampleData {
    var locations: [Location]?
    var locationGroups: [LocationGroup]?
    
    static let sampleLocations: [Location]? = Location.sample
    static let sampleLocationGroups: [LocationGroup]? = [LocationGroup.sample]
}

public struct Location: Hashable, Identifiable {
    var name: String
    var coordinates: CLLocationCoordinate2D
    var photo: String
    public var id = UUID()
    
    static public let sample: [Location] = [
        Location(name: "Best Bagel & Coffee", coordinates: CLLocationCoordinate2D(latitude: 123, longitude: 121), photo: "asdf"),
        Location(name: "Absolute Bagels", coordinates: CLLocationCoordinate2D(latitude: 123, longitude: 121), photo: "asdf"),
        Location(name: "Tompkins Square Bagels", coordinates: CLLocationCoordinate2D(latitude: 123, longitude: 121), photo: "asdf"),
        Location(name: "Zabar's", coordinates: CLLocationCoordinate2D(latitude: 123, longitude: 121), photo: "asdf"),
    ]
    
    static public let oneSample = Location(name: "Absolute Bagels", coordinates: CLLocationCoordinate2D(latitude: 123, longitude: 121), photo: "asdf")
}

public struct LocationGroup: Identifiable, Hashable {
    var name: String
    var locations: [Location]
    public var id = UUID()
    
    static public let sample: LocationGroup = LocationGroup(name: "Bowling", locations: [
        Location(name: "Frames Bowling Lounge", coordinates: CLLocationCoordinate2D(latitude: 123, longitude: 121), photo: "asdf"),
        Location(name: "Bowlero Chelsea Piers", coordinates: CLLocationCoordinate2D(latitude: 123, longitude: 121), photo: "asdf")
    ])
}

extension CLLocationCoordinate2D: Hashable {
    public static func == (lhs: Self, rhs: Self) -> Bool {
        return lhs.latitude == rhs.latitude && lhs.longitude == rhs.longitude
    }
    
    public func hash(into hasher: inout Hasher) {
        hasher.combine(latitude)
        hasher.combine(longitude)
    }
}

Eytan Schulman · Accepted Answer

After a lot of trial and error, and gaining a deeper understanding of how NavigationSplitView, NavigationStack, and NavigationPath can work together, I came up with the following solution, that allows me to push a list onto an existing one, and use NavigationSplitView's detail: to push a detail. While this doesn't support recursive-lists (more than two levels deep), that's not a requirement for my usage.

The "trick" that I learned that allowed this to work, was to use NavigationPath within a NavigationStack in my NavigationSplitView sidebar, in order to push another list onto the detail.

In addition, the trigger of detail: in a NavigationSplitView is from the List(selection:) within the side-bar.

Because I am using the same Binding within both my List and its sub-list, the NavigationSplitView pushes the detail onto the highest stack.

Here's the final result. working on iPhone and iPad:

In order to push a LocationListView onto an existing one, I incorporated NavigationPath:

ContentView

struct ContentView: View {
    @State private var navigationPath = NavigationPath()
    @State private var selectedItem: Location?
    @State private var columnVisibility = NavigationSplitViewVisibility.doubleColumn
    
    var body: some View {
        NavigationSplitView(columnVisibility: $columnVisibility) {
            NavigationStack(path: $navigationPath) {
                LocationListView(
                    locationData: LocationSampleData(
                        locations: LocationSampleData.sampleLocations,
                        locationGroups: LocationSampleData.sampleLocationGroups
                    ), selectedItem: $selectedItem,
                    navigationPath: $navigationPath)
                .navigationDestination(for: LocationGroup.self) { locationGroup in
                    LocationListView(
                        locationData: LocationSampleData(locations: locationGroup.locations), selectedItem: $selectedItem,
                        navigationPath: $navigationPath
                    )
                }
            }
        } detail: {
            if let selectedItem = selectedItem {
                LocationDetailView(selectedLocation: selectedItem)
            }
        }
    }
}

LocationListView

struct LocationListView: View {
    var locationData: LocationSampleData
    @Binding var selectedItem: Location?
    @Binding var navigationPath: NavigationPath
    
    var body: some View {
        List(selection: $selectedItem) {
            if let locations = locationData.locations {
                ForEach(locations) { location in
                    NavigationLink(value: location) {
                        Text(location.name)
                            .bold()
                    }
                }
            }
            
            if let locationGroups = locationData.locationGroups {
                ForEach(locationGroups) { locationGroup in
                    Button(action: {
                        navigationPath.append(locationGroup)
                    }) {
                        Text(locationGroup.name)
                            .bold()
                            .foregroundStyle(.red)
                    }
                }
            }
        }
        .navigationTitle("Saturday Spots")
        .navigationBarTitleDisplayMode(.large)
    }
}