watchOS 4.0

This article summarizes the key developer-related features introduced in watchOS 4.0, which runs on currently shipping watchOS devices. The article also lists the documents that describe new features in more detail.

For late-breaking news and information about known issues, see Release Notes at

For the complete list of new APIs, choose Show API Changes from the dropdown at the top of any page of the API Reference documentation.

To learn about what’s new in Swift, see Swift Language and The Swift Programming Language (Swift 4).

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