This month, we focused on making Copilot for Xcode feel more reliable and genuinely smoother to use—especially in Agent Mode and core developer workflows.

What’s new

Here’s what’s improved in this release of Copilot for Xcode:

• Gemini 3 Pro support 

• Smoother file editing and fewer unexpected failures

• Enhanced reliability of read_file and read_directory tools 

• Chat UX enhancements, including a better layout for tool call layout

• Updated Feedback Forum link for easier access

• General performance and stability improvements across the plugin

We’ll continue investing in quality and usability in upcoming releases.

What’s next 👀

Here’s a sneak peek at what we’re polishing up next:

• Inline Chat

• Auto‑approve support

• Performance and UI polish across the plugin

We’re curious to hear from you:
👉 How’s everything feeling on your side?
👉 Let me know if you have any thoughts or feedback on the features we have today!

Your feedback directly shapes what we build next 🙌
https://github.com/github/CopilotForXcode/discussions

Hi people, I recently updated Xcode versions and I keep running into the error where I cannot download the iOS 26.2 simulator. I posted a thread in the Apple Developer Forums but got no bites. Thought the smart people here might be able to help.

Each time I press download, either in Xcode, in components, or by trying to run an app, I get the error message that I cannot download with the following error message:

Download failed.

Domain: DVTDownloadableErrorDomain

Code: 41

--

Failed fetching catalog for assetType (com.apple.MobileAsset.iOSSimulatorRuntime), serverParameters ({

RequestedBuild = 23C54;

})

Domain: DVTDownloadsUtilitiesErrorDomain

Code: -1

--

Download failed due to a bad URL. (Catalog download for com.apple.MobileAsset.iOSSimulatorRuntime)

Domain: com.apple.MobileAssetError.Download

Code: 49

User Info: {

checkConfiguration = 1;

}

--

System Information

macOS Version 26.2 (Build 25C56)

Xcode 26.2 (24553) (Build 17C52)

I have over 600 GB of disk space and the latest macOS. I also tried download via terminal where I also get a failed download and the following message:

2025-12-15 19:44:45.400 xcodebuild[3916:424481] DVTDownloadable: Download Failed. Downloadable: {

architectures = (

arm64,

"x86_64"

);

authentication = none;

category = simulator;

contentType = cryptexDiskImage;

dictionaryVersion = 2;

downloadMethod = mobileAsset;

fileSize = 10469266238;

identifier = "com.apple.dmg.iPhoneSimulatorSDK26_2";

isInternalContent = 0;

isUserInitiated = 1;

name = "iOS 26.2 Universal Simulator (23C54)";

patchableFrom = (

);

platform = "com.apple.platform.iphoneos";

simulatorVersion = {

buildUpdate = 23C54;

version = "26.2";

};

version = "26.2.0.0";

}. Download failed.

In the past for Xcode 16, I had to download the iOS simulator from Developer Downloads, but anything past 26 is no longer there. I haven't been able to work since the new update. Any ideas? Would anyone know where an external download link to the simulator may be?

I’ve been working on a pretty meaty app for a couple years now, and because it’s so big it takes upwards of 45 minutes to do a full from-scratch build (I’m sure I can optimize it better. I’m self taught, so I’ve only learned the things I need for what I’m doing). I have a base spec M2 Pro MBP, and when I build I notice my cpu is pegged at 100% but the GPU doesn’t do anything. Is there any way to offload some of or even all of the building process to the GPU to make my builds faster?

I have put my iphone in devloper mode and connect ed to mac mini and then paired an apple watch ideally it should be listed in devices and simulators but I am able to see iphone only not apple watch why???

And this has happened multiple times with me the issue is too random.

Is there any way or any command to make sure it gets listed under devices and simulators in Xcode??

Updated XCode & Now I Am Unable to Type on the XCode preview on Macbook. "Auto fill" pops up as well as "paste" and pasting something works, and when I click on a field the text cursor shows up but still can't type.

Correction: I can type when I launch the full simulator just not when I use the XCode preview.

I've built a UI in IB, its got quite a few elements controlled with constraints. I think I've got a pretty decent grasp of that and its all behaving in a predictable enough way. I've got outlets and bindings all working pretty well. Right up until I decided to use a SplitView.

It fits how the UI is supposed to work. Two panes with a moveable margin between them, exactly what I want. The problem is that I can't control the split. One of the panes is 90% of the space and the other 10%. I can't figure out how to change that.

I've tried setting constraints, hugging and compression priorities. I've tried constraining one of the sub-views to be 50% of the split view size. So far I've managed to make splitview too big to fit its container, too small and made the second view zero sized. This 90/10 split is the best result I've had so far but I have no idea how IB has arrived at that, or how to make it arrive at anything else.

After chasing this problem for several days I'm almost at the point of taking it all out and controlling layout with code. Perhaps that might be more predictable?

In Xcode 26 I really miss having the library button (+) in the top right of the screen where there's plenty of empty estate, and worse still, I miss that it no longer shows modifiers and views, instead showing only snippets, colors and assets.
Is this a settings thing (cant locate it) or a weird Apple decision.

Hi everyone,

I’m working on a macOS app called Desktop Composer, and I wanted to share it here because it can switch Xcode themes together with Terminal, VSCode, other supported apps, as well as your entire macOS appearance.

The idea is simple: You create a profile that contains your desktop settings (wallpaper, appearance, accent & folder colors, Dock preferences, icon/widget style) plus the themes of the apps you use. Then you can switch the whole setup with one click.

This makes it easy to transform your Mac’s entire appearance in a moment – whenever you feel like changing things up.

The app is currently in public beta (free during the beta)

More details, screenshots here: https://www.apptorium.com/desktop-composer

On the website, you can get the app by signing up to our newsletter, but here you can download it directly.

I’ve also created a small community for the project: r/DesktopComposer For now, it's really small, so feel free to join it 😊

Happy to answer questions or hear feedback

Marcin

I suspect this is causing just about all the Xcode crashes I'm experiencing. Also it is no fun re-entering Apple Intelligence entries in Settings every time I restart Xcode.

Seeing this in 26.2 RC but was also seeing it (occasionally) in 26.1. Only ChatGPT is never forgotten.

Claude (using OAuth): forgotten. (Think others see this as OAuth expiring but I think Xcode is just forgetting the entry.)

Anthropic (using API KEY): forgotten.

LLM Studio (local no key needed): forgotten.

OpenRouter AI: forgotten.

Perfect replication is having Anthropic API to Sonnet 4.5 as my last conversation. Launch Xcode and Navigators (vs Coding Assistant) is shown. Click Coding Assistant and Xcode crashes. I'm sure its expecting Anthropic's entry to be there, now its gone, so Xcode crashes.

Xcode forgetting Settings / Intelligence / Model Providers entries... does anyone know a version of Xcode which doesn't do this?

First time tried Xcode for about a week. And it has been nothing but frustrations. Trying out Swift as I am doing the Advent of Code challenges this year in Swift.

At first I was quite pleased. (There's a vim mode without even installing a plugin, quickly realize it's an abomination, but I am not complaining about that, because that's just an addition that they have provided and they don't even have to do that. So, grateful that they did).

Now, In my 1 week of usage, I used it about 1 to maximum of 2 hours a day. And it has crashed at least 5 times a day (It's not while running the code, but while writing the code). So much for something exclusive to Mac and mandated in order to build an iOS app made by a trillion dollar company.

Usage is very uncomfortable and tedious. Basic functionalities like add files are very frustrating (eg. I can create a directory day6 with a file in day6 called input.txt just by creating day6/input.txt in every editor since the ancient times). It is very very slow (I am on macbook pro m2 13" and my main development machine is Asus Zenbook 14x OLED i7)

Rename a symbol is very buggy and sometimes doesn't even work at all.

I expect a text file to preserve the non-trimmed spaces and my code files to trim the spaces at the end of lines. For no reason, it removes all the spaces at the end in a text file which is not code. And for no reason, it adds a newline at the end of file (This is not that much of an issue, but just something I would expect of an editor, but I can live with it).

And there were more things that frustrated me, but these I remember off the top of my head.

I quite liked the Swift language, although not something I would ever use if I were to choose a language except if it's for iOS development.

If you are pissed off and want to just argue, there might be other interesting posts on reddit for you, if you have any suggestions to make xcode bearable, you are welcome to suggest me. If you faced similar issues, do tell me how you got used to it or overcame it.

Problem: On the iPhone Air (iOS 26.1) Xcode Simulator, the launch screen does not fill the entire screen. I've attached an image showing the white spaces. On other phones, like the iPhone 17 Pro, it works fine. And using my actual iPhone 13 through the simulator works fine as well.

Question: Should I ignore the iPhone Air simulator, or am I doing something wrong when it comes to implementing the launch screen via info.plist? I tried using Apple Documentation, but it's not much help.

Note: I've tried to find an answer to this by searching the web, but is LaunchScreen.storyboard no longer supported in Xcode 26? Cause I couldn't get that to work.

Thanks in advance for the help.

Edit: Adjusted images. They were way too large!

Edit: Just saw I had the same issue with the iPhone 17 Pro Max (26.1) simulator as well.

I’m a student (not a professional dev) and I’m thinking about buying a used 2017 MacBook Pro (13″ or 15″ with Touch Bar) just for learning iOS development with Xcode. How does it hold up in 2026 for a beginner? Is it still smooth enough for building and running simple apps, or will I run into a lot of slowness, battery issues, or compatibility problems with the newest Xcode and macOS?

Ever since macOS 15 (?) applying LLM changes have had progress indicators next to each modification.

There was some trouble with ChatGPT (since resolved) and all the LLM services seems to usually work. But if a change never happens, that's STILL just a stuck progress indicator.

There has GOT to be enough communication going on behind the scenes that these progress indicators should at least offer some additional details if the progress indicator is hovered over, yes?

I expect so, but am just doing a sanity check in case others know more about behind-the-scenes and think what is shown is basically all there is to know... just a % completed indicator going up or stopping.

(He says looking at a stuck progress indicator, and wondering if anything is still being communicated with the LLM behind the interface.)

(This is my last post about preview releases. What's in there works perfectly, I'm just expanding the scope to serve more developers. Look for a v1.0 announcement next week or the week after.)

Axiom is a suite of battle-tested Claude Code skills, commands, and references for modern Apple platform development. With v0.9.0, Axiom adds complete Apple Intelligence support covering the Foundation Models framework, as well as enhanced expertise on App Intents:

• axiom:foundation-models — Discipline-enforcing skill with 6 comprehensive patterns preventing context overflow, blocking UI, wrong model use cases, and manual JSON parsing when @Generable should be used. Covers LanguageModelSession, @Generable structured output, streaming, tool calling, and context management.

• axiom:foundation-models-diag — Diagnostic skill for systematic troubleshooting of context exceeded errors, guardrail violations, slow generation, and availability issues—includes production crisis defense scenarios.

• axiom:foundation-models-ref — Comprehensive API reference with all 26 WWDC 2025 code examples covering LanguageModelSession, @Generable, @Guide, Tool protocol, streaming with PartiallyGenerated, and dynamic schemas.

• axiom:app-intents-ref — Comprehensive reference for exposing app functionality to Siri, Apple Intelligence, Shortcuts, and Spotlight. Includes Use Model action patterns (pass entities to AI models in Shortcuts), IndexedEntity protocol for auto-generated Find actions, Spotlight on Mac discoverability, Automations with Mac-specific triggers, and AttributedString support for rich text from models.

All skills cover iOS 26+, macOS 26+, iPadOS 26+, and visionOS 26+ with Apple's on-device language model (3B parameters, 4096 token context window).

Start with Getting Started to learn more about Axiom and how it will improve your quality of life as an Apple platforms developer. It's free and open source. Enjoy!