Here, you’ll find documentation about the Swift language and the standard library. Apple has additional resources for learning Swift—such as videos, sample code and playgrounds, and additional documentation—at https://developer.apple.com/swift/resources/.
The Swift Programming Language
The Swift Programming Language is the authoritative reference for Swift, offering a guided tour, a comprehensive guide, and a formal reference of the language. You can download the latest version below.
The Swift Programming Language (ePub)
This ePub document is made available under a Creative Commons Attribution 4.0 International (CC BY 4.0) License.
Although the ePub of The Swift Programming Language above is provided in English, we encourage you to participate in translating this document to other languages. The best way to do so is to get involved with an existing translation project or start a new one where there’s a need. A great example of this is the GitHub project for the Chinese translation:
The Swift Programming Language (Chinese translation, GitHub project)
If you know of a quality translation project underway, please let us know on the swift-dev mailing list, and we’ll do our best to provide a link to that project from this page.
API Design Guidelines
One of the goals of the Swift 3.0 release is to set a uniform standard for the programmer’s user experience, much of which is defined by the names and idioms that appear in APIs. The result is a set of design guidelines that explain how to ensure your code feels like a part of the larger Swift ecosystem.