Reverse-Engineering Xcode's Coding Intelligence prompt
by Peter Friese
Xcode 26’s Coding Intelligence is one of the most exciting new features for iOS developers, bringing AI-powered code assistance directly into Apple’s IDE.
I was super excited to try this out, but wasn’t able to make the ChatGPT integration work. Fortunately, Xcode also supports a BYOM (bring your own model) approach, so I decided to use Gemini 2.5 Pro.
Gemini provides an OpenAI-compatible API, so setting it up should be easy, right? Well, it turns out that it’s slightly more complicated than that. Thanks to Carlo Zottmann’s excellent blog post, I was able to get it working.
The trick is to use Proxyman for URL rewriting. And that opens up a whole new world of possibilities - for example, you can intercept the communication between Xcode and the underlying LLM, and see exactly what’s going on.
In my article, I disseminate the system instructions, user prompts and tool calling mechanisms that power Xcode’s Coding Intelligence feature to help you understand how it works under the hood. It’s a fascinating look into the inner workings of Apple’s AI-powered coding assistant, and quite enlightening. If you thought that coding agents are a black box, this article will open your eyes. It’s less magic, and more elbow grease than you thought.