Introduction

This document describes developer-level features that were introduced in different versions of watchOS. For each shipping release, this document provides links to “delta” reference documents, which list the new and changed programming interfaces that were introduced in that release.

These are the main websites where you can obtain watchOS development support:

• developer.apple.com: The best source of official up-to-date technical documentation on watchOS development

• https://developer.apple.com/watchOS: The macOS Dev Center homepage on the Apple Developer website

• https://forums.developer.apple.com/community/app-frameworks/watchkit: A dedicated Apple Developer Forum for watchOS.

Organization of This Document

This document includes the following articles:

watchOS 4.0 describes the new and updated features in watchOS 4.0.

watchOS 3.2 describes the new and updated features in watchOS 3.2.

watchOS 3.0 describes the new and updated features in watchOS 3.

watchOS 2.2 describes the new and updated features in watchOS 2.2.

watchOS 2.1 describes the new and updated features in watchOS 2.1.