I've submitted a bug report myself and will see if I can find a workaround. Thanks! I am actually kind of "unblocked" in a different way by building my own custom component: @main struct StepperDemoApp: App { func onIncrement() { print(#function) } func onDecrement() { print(#function) } var body: some Scene { WindowGroup { VStack { Text("Stepper") Button("Increment") { self.onIncrement() } Button("Decrement") { self.onDecrement() } } .padding() } } } This unblocks my use case for my app… but I am still blocked from using the system Stepper component. If I did ship this custom component as a workaround it would be helpful for my repo to be able to explain to readers why this workaround is needed (because the production stepper component is potentially causing a bug on macOS).

This is a more detailed example that shows some extra work from my production app: @main struct StepperDemoApp: App { var body: some Scene { WindowGroup { ContentView() } } } @Observable final class Number { var value: Int = 0 } struct ContentView: View { @State private var number = Number() func onIncrement() { number.value += 1 print(#function) } func onDecrement() { number.value -= 1 print(#function) } var body: some View { Stepper { Text("Stepper \(number.value)") } onIncrement: { self.onIncrement() } onDecrement: { self.onDecrement() } .padding() } } #Preview { ContentView() } In this example, the Stepper text label value depends on state (the number class), but I see the same unexpected behavior (potential bug) from my original example. My Stepper text label is correctly updating when the Observable value changes… but the onIncrement and onDecrement closures are in some kind of "bad" state. My original example showed how the Stepper behaves unexpectedly when no state is triggering a redraw. This new example behaves unexpectedly when state is triggering a redraw through an Observable object. Our previous example showed how Stepper behaves as expected when we trigger a redraw directly on state (without the indirection of an Observable object). All these repros are from macOS 14.6.1… deploying to iPhone simulator behaves as expected on all examples (no unexpected behavior).

Hmm… I believe I do now have an understanding how a State variable would tie the lifecycle of its value to the lifecycle of a View component… but I am still unclear how this helps me to understand how a State variable defined on an App component can be expected to behave: https://developer.apple.com/documentation/swiftui/managing-user-interface-state This article has many examples of using State in a View component… but I do not see examples of using State in our App component. https://developer.apple.com/videos/play/wwdc2020/10040/?time=1852 This video does have an example of a StateObject being used as a global "source of truth" (which is going to be most similar to my use case)… but this video predates the release of State and Observable. https://developer.apple.com/videos/play/wwdc2023/10149 I believe this video has a close example from FoodTruckModel to achieve a similar feature to my use case. What this video seems to be missing is where this FoodTruckModel should first be created. Similar to the previous talk… this "global source of truth" looks like it should belong in my root App component… but then would that imply that FoodTruckModel be better initialized as a State var or as a regular Swift let? A side-question I would have here is how it would be possible for an engineer to stress-test their app in a way to cause the App component instance to be disposed by SwiftUI (and then rebuilt while the process is running). Is such a use case ever possible in an edge case? Is this something (recreating App component) that engineers should ever have to prepare for to defend against?

Does not repro from Xcode Version 16.2 and macOS 15.2. Thanks! :D

https://github.com/apple/sample-food-truck/blob/3954a769e99f3cc53297d94f2b960ceb2665b3d6/App/Orders/OrderDetailView.swift#L87-L110 I had another question about using Live Activities from Xcode Preview. My question is from a different POV: I have a view component that performs some logic to start and end live activity. I am wondering… what kind of support do I have from Xcode Preview to then actually see that Live Activity in action as a kind of "end to end" test that my call to ActivityKit.Activity started an activity correctly? My understanding here is the supported way to test Live Activity starting and stopping is to actually run the app and start the activity from that component. There isn't a supported "shortcut" from Xcode Preview. Is that correct?

If the find a bug in the sample code please file a big report via Feedback Assistant and post the FB number here once you do. https://appleinsider.com/articles/25/04/18/when-you-report-bugs-on-ios-some-content-may-be-used-for-ai-training Thanks… but for privacy reasons I'm currently blocked on submitting bug reports due to a requirement on AI training. Are you referring to the dismiss environment property? I'm referring to the Select and Done buttons that appear to toggle EditMode: