Very excited for all of the nice things Foundation Model access unlocks in iOS 26. Makes things like automatic tag suggestion in Crouton super smooth.

natashatherobot.com/p/apple-founda…

New Blog Post: How to Add Custom Guardrails to Your FoundationModels Generation Learn how to add custom guardrails to Apple’s on-device FoundationModels framework to validate and filter user input using structured prompts and model-generated reasoning. Link below in comments!

Don't miss this new guest blog post by Tarek M. Ben Lechhab! LLMs Calling LLMs: Building AI Agents with Apple's Foundation Models and Tool Calling Explore going from prompts to multi-agent architecture by leveraging Foundation Models tool calling capabilities and exposing LLMs themselves

Still not all! Here’s a few more FoundationModels changes in beta 4: - Your tools can now return any `PromptRepresentable` (like a string, or a Generable model) instead of `ToolOutput` (which is no longer supported) - Use `logFeedbackAttachment` when filing FB’s to easily

NatashaTheRobot Julian Schiavo Ok, that’s good to hear! We are tracking a known issue: the framework may throw a guardrail violation for all prompts, where the actual reason is that the model assets haven’t been fully downloaded. (FB18944619)

New Blog Post: Using the FoundationModels Framework for Streaming from external LLM providers Link below in comments...

There is a new refusal case with explanation. They explicitly mention that a token is 3-4 characters in English. I had asked for a property to keep count of it in a feedback but the response was that it is not on the engineering team's roadmap

Biggest change in foundation model framework! There is a new permissiveContentTransformations guardrail!

iOS 26 Beta 5 dropped today and contains some exciting additions to the Foundation Models framework. (1/6)

Shihab Mehboob You need to recompile your app using Xcode 26 beta 5 to run the app on OS 26 beta 5. We made some final API improvements and removed APIs that were deprecated in previous betas.

If you missed the WWDC25 recap broadcast, video is now on Youtube! I cover: - On-device LLM using the Foundation Models framework - Custom models using CoreML - Latest research models using open-source MLX and more! Enjoy! youtube.com/watch?v=9lO3ds…

Rudrank Riyam That’s right — guardrails will no longer be triggered by sensitive/controversial topics that are not fundamentally unsafe. If you ask the model to summarize or rewrite such content, the model will do as told; otherwise, the model may still refuse with an explanation.

The team that built the Foundation Models framework is hiring! Join us to create the best LLM APIs, both for app developers and for Apple teams. jobs.apple.com/en-us/details/…

9/11だけではありますが、Foundation Model フレームワークのエンジニアも参加してくれることになりました。もし直接エンジニアと話したいって方は9/11にぜひご応募ください。また、9/9,10の枠も、もちろんお待ちしております。

My Dark Noise update with the new iOS 26 Liquid Glass design, and a new Magic Mix feature (demoed here) powered by the new Foundation Model API & Apple Intelligence is ready for tomorrow's release! If you're press writing about app updates, my press release is below 🧵👇

Prime example for how to apply Foundation Models in your app

Trying out lots of new apps from App Store today! Love all these delightful features leveraging our on-device LLM 🤩 #iOS26

A list of apps that are using Apple's local models to introduce new features. techcrunch.com/2025/09/19/how…

apple.com/newsroom/2025/…