SwiftAI – open-source library to easily build LLM features on iOS/macOS
We built SwiftAI, an open-source Swift library that lets you use Apple’s on-device LLMs when available (Apple opened access in June), and fall back to a cloud model when they aren’t available — all without duplicating code. SwiftAI gives you: - A single, model-agnostic API - An agent/tool loop - Strongly-typed structured outputs - Optional chat state Backstory: We started experimenting with Apple’s local models because they’re free (no API calls), private, and work offline. The problem: not all devices support them (older iPhones, Apple Intelligence disabled, low battery, etc.). That…
In plain words
SwiftAI is an open-source Swift library for iOS and macOS that enables developers to build language model features using Apple's on-device LLMs when available, with automatic fallback to cloud models on unsupported devices. It provides a single model-agnostic API, an agent/tool loop, strongly-typed structured outputs, and optional chat state management, eliminating the need for duplicate code across different model implementations. This approach leverages free, private, offline on-device processing while maintaining compatibility across the Apple ecosystem.
written from the facts on this page · September 2026
From the sources
In the maker’s words, at launch
We built SwiftAI, an open-source Swift library that lets you use Apple’s on-device LLMs when available (Apple opened access in June), and fall back to a cloud model when they aren’t available — all without duplicating code. SwiftAI gives you: - A single, model-agnostic API - An agent/tool loop - Strongly-typed structured outputs - Optional chat state Backstory: We started experimenting with Apple’s local models because they’re free (no API calls), private, and work offline. The problem: not all devices support them (older iPhones, Apple Intelligence disabled, low battery, etc.). That meant writing two codepaths — one for local, one for cloud — and scattering branching logic across the app. SwiftAI centralizes that decision. Your feature code stays the same whether you’re on-device or cloud. Example import SwiftAI let llm: any LLM = SystemLLM.ifAvailable ?? OpenaiLLM(model: "gpt-5-mini", apiKey: "<key>") let response = try await llm.reply(to: "Write a haiku about Hacker News") print(response.content) It's open source — we'd love for you to try it, break it, and help shape the roadmap. Join our discord / slack or email us at [email protected]. Links - GitHub (source, docs): https://github.com/mi12labs/SwiftAI - System Design: https://github.com/mi12labs/SwiftAI/blob/main/Docs/Proposals... - Swift Package Index (compat/builds): https://swiftpackageindex.com/mi12labs/SwiftAI - Discord https://discord.com/invite/ckfVGE5r and slack https://mi12swiftai.slack.com/join/shared_invite/zt-3c3lr6da...
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