Foundation Models Framework — Complete API Reference

Overview

The Foundation Models framework provides access to Apple's on-device Large Language Model (3 billion parameters, 2-bit quantized) with a Swift API. This reference covers every API, all WWDC 2025 code examples, and comprehensive implementation patterns.

Model Specifications

Technical Details:

• Parameters: 3 billion (3B)
• Quantization: 2-bit
• Context Window: 4096 tokens (combined input + output)
• Supported Languages: English + additional languages via SystemLanguageModel.default.supportedLanguages
• Platforms: iOS 26+, macOS 26+, iPadOS 26+, axiom-visionOS 26+