---
title: "Three Apple language paths"
lesson_id: "01"
---

# Three Apple language paths

- **Lesson ID:** 01
- **Goal:** Name SystemLanguageModel, PrivateCloudComputeLanguageModel, and CoreAILanguageModel as the three backs.
- **Human lesson:** [01-three-apple-language-paths.html](01-three-apple-language-paths.html)

## Prerequisites

- iOS 27 or macOS 27.

## Inputs, outputs, and artifacts

- **Inputs:** A task that needs a language model.
- **Outputs:** A map from task class to a candidate back.

## Agent build steps

1. Describe each type in one sentence: on-device, PCC, custom Core AI.
2. Show illustrative Swift bindings for the three types.
3. Leave third-party servers out of scope.
4. Call out availability as a required branch.
5. Preview Dynamic Profile model modifiers.

## Constraints

No LiteLLM. No Python. No em dashes. Cite [WWDC26 241](https://developer.apple.com/videos/play/wwdc2026/241/) lightly. Swift sketches only.

## Key concepts

- `LanguageModel` backs `LanguageModelSession`. Three conforming types matter here.
- `SystemLanguageModel` runs on the device. Lowest latency. Smallest window. No network.
- `PrivateCloudComputeLanguageModel` runs Apple's larger PCC model. No API key.
- `CoreAILanguageModel` wraps a baked `.aimodel` for a job you shipped.

## Takeaways

- Same session protocol, different back. Dynamic Profiles switch the model with a modifier.
- MLX and third-party servers are out of scope for this course.
- The router must check availability before it picks.

## Acceptance checks

- All three types are named.
- Swift bindings are shown.
- Availability is mentioned.
- Agent brief link is present.