Xcode

i am using xcode 26.0. If i deploy it from there on my phone running 26.1 or 26.2 i get the strange flip. but if i instead deploy it on one running 18.5 (all iphone pros) , the animation is wrong.

We are encountering the same issue since Xcode 16. We run XCTest and Swift Testing. For us it is flaky, sometimes some local Packages (SPM) are missing in the .xcresult file, resulting in a Coverage of 0% for these packages

You were right. We've found out that the issue was that we registered an observer with addObserver using a #selector that pointed to a function marked as @MainActor, but we were calling the NotificationCenter.post method from a background thread. Apparently this caused the main-actor isolation check to fail, which led to a crash. Even though there is no data-race or UI operation in the function, looks like it is enough for the function to be @MainActor to cause a crash when called from outside the main thread. We fixed it by making sure the relevant NotificationCenter.post calls are executed on the main thread. Initially, we thought that marking the function with @MainActor would prevent it from being called from a nonisolated context by producing a compile-time error in Swift 6 mode. But since a Selector instance is not aware of the actor isolation of the target function, Xcode is not able to show a warning and it caused us to not realize the issue at first. I appreciate your guidance @DTS Engineer.

Thanks for the post and the description. Never seen this, so I don't think is a bug, what version of Xcode are you using? Have you updated to the latest? Could you please provide a list of the macOS, Xcode, and simulator/physical device versions? Do you get the same results with just the relevant code in a small test project? If so, please share a link to your test project. That'll help us better understand what's going on. If you're not familiar with preparing a test project, take a look at Creating a test project. Albert Pascual
  Worldwide Developer Relations.

Hi I share the code of function that launches the stream query: func lanzarPeticion() async{ defer{👎🔘lanzarConsulta.toggle()} do { let sessionStream = LanguageModelSession(model: modelStream, instructions: instructions) let genOptions = generarSamplingMode(temperatura: temperatura, maxResponseTokens: maxResponseTokens, probabilityThreshold: probabilityThreshold, topK: topK, seed: semilla) let responseStream = sessionStream.streamResponse( to: prompt, options: genOptions) for try await partial in responseStream { withAnimation{ self.respuesta = partial.content t.createPartialTime() } } withAnimation{ t.stop() } } catch { // all the logic for errors } } Clarifications about the code: First of all, English is dominant on code but sometimes use Spanish, my native language, specially when terms overlap swift or framework ones; I have my own emoji rules to avoid characters an improve readability (at this moment I'm indie developer so I set the rules) The defer block is to free the button that launches the request

Thank you! Developer feedback is vital to making Xcode even better. If you have any other feedback, please use the Feedback Assistant. You can access Feedback Assistant directly from Xcode, and use it to report issues you encounter or request enhancements to tools and services.

Thanks for the post, I am not familiar with the third party React Native. You should check with the support resources provided by the 3rd party to get assistance with their software. Unless another developer in the forums has experience with the third-party and can provide assistance. My sole recommendation is to ensure that your macOS is updated to the most recent version, as well as your Xcode. Additionally, I suggest contacting React Native support to inquire if they have encountered similar issues. Good luck. Albert Pascual
  Worldwide Developer Relations.

@Zhaocheng Please try the new Xcode that is currently in beta to see if fixes your issue. Let me know what results do you get please. Thanks @marceloamx Albert Pascual
  Worldwide Developer Relations.