@davedelong @stroughtonsmith Make sure you’re signed up for “Meet with Apple” emails here. They announce upcoming activities like this one. https://developer.apple.com/account#EmailsCard

@kylebshr you have to put the HStacks in before you pass the view to Group(subviews:)

@kylebshr This happens because you’re allowed to return multiple subviews from your `Item` view, and then have the `Group(subviews:)` modify each one independently. There’s a similar conundrum with `backgroundProminence` in the environment and the approach documented there should help with your environment property too: https://developer.apple.com/documentation/swiftui/environmentvalues/backgroundprominence

RE: https://infosec.exchange/@madcoder/115466826731130245

Now I finally understand why thr C++ member initializer syntax is spelled the way it is

@stefanpauwels Got it, so the issue is that the Release configuration uses your App Store bundle ID instead of the development one. One way to avoid this is to set up a Profiling configuration and use that for the Profile mode of your scheme. It’s definitely important to use the other settings of Release that enable optimizations, as you’ll otherwise waste time fixing perf issues that never affected your customers because they’re fixed by compiler optimizations.

@stefanpauwels Hi, Instruments engineer here! I’d be interested to learn more about your issue. We definitely recommend using the Release config to get the most accurate profiling results. What about that causes you to use the production CloudKit environment? Can you report this using Feedback Assistant and attach the newest file revealed by `open -R /var/folders/**/pbxperfconfig.plist` so we can see what options are being passed to Instruments?

The Profiling Tools team at Apple is looking for interns! We work on the Instruments app, delivering performance insights to developers inside and outside Apple. I’ve really enjoyed this team because we get to work with a lot different people to develop useful tools, and build a lot of personal knowledge along the way.

If you’re interested, feel free to DM me your resume or reply with any questions! In person in Cupertino, for students who will be attending college in the 2026–27 school year.

@simonbs Hi! I’d like to investigate this. Can you report using Feedback Assistant and attach sysdiagnoses from both devices taken after attempting to profile the widget?

@simonbs Also: check if these are categorized as Creation or Update. If they’re all Creation, it could be that setting up this particular view is expensive and you may be able to restructure your app to ensure that the view’s lifetime doesn’t end unless it actually needs to.

@simonbs When I was working on the SwiftUI instrument I knew that not all of the problems it would call out would be fixable directly in your code. (You could of course remove the view from your app entirely, but you probably do want the app to actually do something lol).

I recommend doing Set Inspection Range on the longest interval here and checking Time Profiler to see if any of your code is running inside that update. If not, time to file a feedback, ideally with a small reproducer project!

@tonyarnold Hi! The lack of support on the simulator is a known issue (and reporting it on Feedback Assistant will help us prioritize). The “Failed starting ktrace session” error on Mac is not expected, though. If you’re still seeing this, can you create a Feedback Assistant report with a sysdiagnose and then share the ID here so we can investigate?

@joe @jrose @beccadax@queer.party @slava @QuietMisdreavus objc_msgSend_irate — forwards the message to the object’s manager

@manuel @jsq If you still want that (such as to make a condition more legible when doing on-line code review) you can click on the annotation and choose the option to convert it to a comment which will also hide it to avoid duplication :)

@fsousa Did you get a chance to submit a report about this in Feedback Assistant? I want to make sure this bug doesn’t slip through the cracks :)

@cocoafrog As I understand it, Xcode 26 sets a build setting in new projects that enables the 2 “approachable concurrency” features. I imagine they will also be included in the next language mode, whenever that happens. Separately, new *app* projects get the MainActor-by-default language feature/mode enabled which I don’t believe is on track to be enabled by default for all projects ever.

It's that time of year, WWDC labs! I highly recommend folks to sign up for labs. I will be in the Performance, Power, and stability labs through the entire week. Sign up for a session, whether you have a specific performance issue you want to work through together or just have questions about our existing & new tools. https://developer.apple.com/wwdc25/sessions-and-labs/one-on-one-labs

This year we have a brand new CPU counters instrument that reimagines what profiling CPU counters looks like, rather than manually configuring HW counters you will be given a guided approach with understandable metrics & documentation in guiding micro-optimizations. We hope that this new tool makes understanding & optimizing your code using CPU counters much more approachable for developers of all experience levels.

Watch this Optimize CPU performance with Instruments talk. This talk covers CPU profiling from the ground up, covering CPU profiler, Processor Trace, and CPU Counters. This is a fantastic talk I would recommend to every developer, especially those new to profiling & performance work.
https://developer.apple.com/videos/play/wwdc2025/308

@fsousa No, you shouldn’t need to do that. Can you file a bug report on Feedback Assistant? Please go to Settings → General → “Attach supporting files” in Instruments and try to record again. Then attach the recorded trace file and a sysdiagnose from both the Mac and your Watch. If you send the number here I’ll take a look!

@fsousa It’s definitely supposed to work on watchOS 26. What error message are you getting?

@cocoafrog since it’s source breaking and there’s no new language mode this year you have to opt in and migrate your codebase: https://github.com/swiftlang/swift/blob/ba715db935aaaf16d4ae221df81424b7b9ad27ab/userdocs/diagnostics/nonisolated-nonsending-by-default.md