FoundationModels: On-Device LLM (iOS 26)

Patterns for integrating Apple's on-device language model into apps using the FoundationModels framework. Covers text generation, structured output with @Generable, custom tool calling, and snapshot streaming — all running on-device for privacy and offline support.

When to Activate

• Building AI-powered features using Apple Intelligence on-device
• Generating or summarizing text without cloud dependency
• Extracting structured data from natural language input
• Implementing custom tool calling for domain-specific AI actions
• Streaming structured responses for real-time UI updates
• Need privacy-preserving AI (no data leaves the device)

Core Pattern — Availability Check

Always check model availability before creating a session: