I’ll preface this by saying I’ve submitted a DTS ticket with essentially this exact text, but I thought I’d also post about it here to get some additional input. Apple engineers: the case ID is 14698374, for your reference.
I have an observable class, called NavigationModel, that powers navigation in my SwiftUI app. It has one important property, navigationSelection, that stores the currently selected view. This property is passed to a List in the sidebar column of a NavigationSplitView with two columns. The list has NavigationLinks that accept that selection as a value parameter. When a NavigationLink is tapped, the detail column shows the appropriate detail view per the navigationSelection property’s current value via a switch statement. (This navigationSelection stores an enum value.)
This setup allows for complete programmatic navigation as that selection is effectively global. From anywhere in the app — any button, command, or app intent — the selection can be modified since the NavigationModel class uses the @Observable Swift macro. In the app’s root file, an instance of the NavigationModel is created, added as an app intent dependency, and assigned (might be the wrong verb here, but you get it) to ContentView, which houses the NavigationSplitView code.
The problem lies when more than one window is opened. Because this is all just one instance of NavigationModel — initialized in the app’s root file — the navigation selection is shared across windows. That is, there is no way for one window to show a view and another to show another view — they’re bound to the same instance of NavigationModel. Again, this was done so that app intents and menu bar commands can modify the navigation selection, but this causes unintended behavior.
I checked Apple’s sample projects, namely the “Accelerating app interactions with App Intents” (https://developer.apple.com/documentation/appintents/acceleratingappinteractionswithappintents) and “Adopting App Intents to support system experiences” (https://developer.apple.com/documentation/appintents/adopting-app-intents-to-support-system-experiences) projects, to see how Apple recommends handling this case. Both of these projects have intents to display a view by modifying the navigation selection. They also have the same unintended behavior I’m experiencing in my app. If two windows are open, they share the navigation selection.
I feel pretty stupid asking for help with this, but I’ve tried a lot to get it to work the way I want it to. My first instinct was to create a new instance of NavigationModel for each window, and that’s about 90% of the way there, but app intents fail when there are no open windows because there are no instances of NavigationModel to modify. I also tried playing with FocusedValue and SceneStorage, but those solutions also didn’t play well with app intents and added too much convoluted code for what should be a simple issue.
In total, what I want is:
A window/scene-specific navigation selection property that works across TabViews and NavigationSplitViews
A way to reliably modify that property’s value across the app for the currently focused window
A way to set a value as a default, so when the app launches with a window, it automatically selects a value in the detail column
The navigation selection to reset across app and window launches, restoring the default selection
Does anyone know how to do this? I’ve scoured the internet, but again, no dice. Usually Apple’s sample projects are great with this sort of thing, but all of their projects that have scene-specific navigation selection with NavigationSplitView don’t have app intents. 🤷♂️
If anyone needs additional code samples, I’d be happy to provide them, but it’s basically a close copy of Apple’s own sample code found in those two links.