iPad & NavigationSplitView

[jclardy]

I'm working on a small app using SwiftUI-Navigation and it has been great on iPhone - but now I'm trying to adapt the app to iPad and I'm running into issues. I've searched for NavigationSplitView in discussions/issues but I didn't find anything.

My app is setup like this:

               NavigationSplitView(columnVisibility: $splitViewVisibility) {
                    List(AppModel.Tab.allCases, id: \.self, selection: $selected) { value in
                        switch value {
                        case .transactions:
                            Label {
                                Text("Amounts")
                            } icon: {
                                Image(systemName: "house")
                            }
                        case .settings:
                            Label {
                                Text("Settings")
                            } icon: {
                                Image(systemName: "gearshape")
                            }
                        }
                    }
                } detail: {
                    switch selected {
                    case .transactions:
                    NavigationStack {
                        TransactionListView(viewModel: transactionListViewModel)
                    }
                    case .settings:
                    NavigationStack {
                        SettingsView(viewModel: SettingsViewModel())
                    }
                    default:
                        Text("No selection")
                    }
                    
                }

The problem is if I navigate to a child view in Settings view, then change the selection to .transactions in the sidebar, the "root" view changes correctly, but I still remain in the same navigation stack (IE I am in Settings > About, I tap on Amounts, then I am now seeing Amounts > About - the parent view changes, but not the view on screen.) For iPhone, I have the app in a TabView and things work correctly (Each tab remembers its own navigation) using these same subviews. My desire is to essentially turn my iPhone app tabs, into a sidebar when viewed on iPad and have them function nearly identically.

I haven't used split view at all in my iOS career (Even in UIKit) and I know these APIs are also new for SwiftUI, but I'm wondering if I'm doing something obviously wrong, or if there are any splitview examples using the swiftui-navigation library?

[tgrapperon]

Hey @jclardy. There is a little magic involved to automatically navigate on selection on iPhone, and I'm not sure that the NavigationStack switch you're performing on the fly is supported.
I'm didn't had the opportunity to experiment with SwiftUINavigation and NavigationSplitView yet, but here's what I'd try:

• Refactor the detail view, so there is only one top-level NavigationStack, and perform the switch inside this view's content.
• Don't use NavigationSplitView if it's not behaving has you'd expect, and rely on @Environment(\.horizontalSizeClass) to decide what kind of interface to present (a NavigationSplitView when .regular, or a NavigationStack+Toolbar when .compact).
  Let me know if it helps. Feel free to post a example project if it doesn't.

[jclardy]

I built a small example project, it seems the behavior of swiftui-navigation is slightly different from the built in navigation when in a split view. In this project I have my split view setup using the iOS 16 APIs (NavigationSplitView/NavigationStack/navigationDestination.) On the first list item, I use the built in navigationDestination(for:), on the second screen it is the same data, but using navigationDestination(unwrapping:). The third tab is just a view that has no navigation destinations.

If you tap into the first view, then tap view three, the navigationstack pops back to the base view. If you tap the second view, then tap the third view, the root view is replaced, but no pop happens. This is the behavior I am seeing in my project. The behavior is the same even if I move the NavigationStack to surround the switch (Rather than multiple individual NavigationStacks as it is now.)

SwiftUINavigationTest.zip

[jclardy]

Also wanted to mention - iPhone works perfectly fine - the only issue is when using a split view on iPad (or mac)

[tgrapperon]

Thanks for the repro. Have you been able to run the example on Xcode 14.3b2? I'm not seeing any behavioral difference between the first two cases: Each time I select the "No navigation" option, it pops back to it, whether it's from vanilla or using SwiftUINavigation destinations.

[jclardy]

I just installed the beta, and I'm still seeing the same behavior with the test project. I've recorded a screengrab, first tapping into the "native" navigation detail, then tapping no nav, then tapping into the swiftui-navigation detail, then tapping into no-nav. In the second case the root view is changed, but the stack isn't for some reason.

Simulator.Screen.Recording.-.iPad.mini.6th.generation.-.2023-03-07.at.18.02.13.mp4

[tgrapperon]

Ha yeah, I'm able to reproduce. For some reason, there is no problem when running in a Preview.
The thing is that first navigation is stack based, whereas the second one is binding-based, and they behave (or were behaving) slightly differently.

There was a bug with deep-linking that made the library use some binding magic, but I'm not able to reproduce the issue with Xcode 14.3b2.

It seems that if we'd replace .navigationDestination(unwrapping:…) implementation by a simple:

self.navigationDestination(isPresented: value.isPresent()) {
  if let binding = Binding(unwrapping: value) {
    destination(binding)
  }
}

we would get the same behavior, on iOS 16.4 at least. This would need to be further investigated, especially to check how far it would be working, and if it indeeds works for deeper deep links.

/cc @mbrandonw