Anthropic releases Claude for Foundation Models Swift package, bringing Claude into iOS 27 and macOS 27

Anthropic released Claude for Foundation Models in beta on June 9, 2026—a Swift package that integrates Claude into Apple's Foundation Models framework for developers building on iOS 27, macOS 27, visionOS 27, and watchOS 27.

What's new

According to the documentation, "Claude for Foundation Models is a Swift package that makes Claude available as a server-side language model in Apple's Foundation Models framework. The package conforms Claude to the framework's LanguageModel protocol, so you drive it with the same LanguageModelSession API you use for Apple's on-device model: respond(to:), streaming, guided generation, and tool calling all work the same way."

Practically, an iOS 27 app can call Claude through a single constructor, passing a ClaudeLanguageModel to LanguageModelSession alongside any other Foundation Models provider. The package supports model constants for Sonnet 4.6, Opus 4.8, and others, plus custom model instances for unreleased IDs. Effort levels including xhigh and max are available—levels not accessible through the standard Foundation Models framework API. Server-side tools (web search, web fetch, and code execution) run on Anthropic infrastructure without device-side invocation. Streaming and structured output via the @Generable annotation are both supported.

Requests go directly from the app to the Claude API. Apple is not in the request path and does not see prompts or responses. Usage is billed to the developer's Anthropic account at standard API pricing.

For production deployments, the package supports a proxied authentication mode that routes requests through a developer-controlled backend, so the shipping app carries no Anthropic API key. The package is available at github.com/anthropics/ClaudeForFoundationModels under an Apache 2.0 license. Xcode 27 (beta) is required.

Context

Apple introduced the Foundation Models framework in iOS 27 and macOS 27 as a unified API spanning on-device and server-side AI. The framework abstracts the model provider behind a common protocol, allowing developers to swap models without rewriting session logic. Anthropic's package is among the first third-party implementations of that server-side protocol.

The release landed alongside the June 9, 2026 Claude Fable 5 and Claude Managed Agents updates, as part of a broader wave of platform integrations Anthropic shipped that day.

Why it matters

For iOS and macOS developers, the practical upshot is straightforward: no separate AI SDK to learn. Apps already using Foundation Models can add Claude without changing the session model, which also makes fallback logic between Apple's on-device model and Claude relatively simple to implement. The documentation recommends escalating to Claude "when you need larger context, frontier reasoning, or server-side tools such as web search and code execution."

Apple's Foundation Models framework has tens of millions of registered developers in its addressable ecosystem. Being a native LanguageModel conformance—rather than a third-party SDK bolted on the side—positions Claude directly in the path of Swift developers who reach for Foundation Models as their default AI layer. The beta label means the API surface may still shift, but the early availability gives Anthropic a foothold in the Apple platform ecosystem before the OS 27 general release.