Foundation Models Chat App Tutorial

A comprehensive iOS chat application demonstrating the new FoundationModels framework introduced in iOS 26. This tutorial app showcases how to integrate on-device large language models (LLMs) with custom tools and real-time chat functionality.

🎯 Overview

This chat application serves as a practical example of Apple's FoundationModels framework, featuring:

• On-device LLM integration using FoundationModels
• Custom tool implementation for calendar event creation
• Real-time chat interface with SwiftUI
• MVVM architecture for clean code organization
• Tool calling capabilities that allow the AI to interact with system APIs

🔧 Features

Core Functionality

• Interactive chat interface with on-device AI responses
• Real-time typing indicators and message timestamps
• Automatic model availability detection and user feedback
• Calendar event creation through natural language commands

Technical Highlights

• FoundationModels Framework: Leverages Apple's new on-device LLM capabilities
• Tool Integration: Custom CreateEventTool that allows the AI to create calendar events
• EventKit Integration: Seamless calendar access with proper permission handling
• Reactive Programming: Uses Combine for state management and UI updates

📱 Requirements

• iOS 26.0+
• Xcode 26+ (Required for FoundationModels framework)
• Apple Intelligence enabled on the device
• Calendar access permissions

🔑 Key Components

OnDeviceLLMManager

The heart of the LLM integration, handling:

• Model availability checking across different states
• Session management with tool integration
• Response generation with error handling
• Publishing loading states for UI updates

CreateEventTool

A custom tool implementation that:

• Conforms to the Tool protocol from FoundationModels
• Uses @Generable and @Guide for parameter definition
• Integrates with EventKit for calendar operations
• Provides structured responses back to the LLM

ChatRepository

Manages chat data flow:

• Message storage and publishing
• Coordination between user input and LLM responses
• Model availability status communication

📚 Learning Resources

This tutorial demonstrates key concepts from:

• Apple's FoundationModels Documentation
• EventKit Framework Guide

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Note: This tutorial requires the latest iOS 26 beta and may require adjustments as the FoundationModels framework evolves during the beta period.