Learning Swift, 3rd Edition

Chapter 2. The Swift Programming Language

The Swift programming language was first introduced in June 2014 at Apple’s World‐wide Developers Conference (WWDC). Swift was a surprise to everyone: Apple had managed to develop an entire language (as well as all of the supporting libraries, developer tools, and documentation) and make it work seamlessly with the existing Objective-C language. And on top of that, it was a really good “1.0” language.

Swift was open sourced on December 3, 2015 and is now as much a community-run project as it is run by Apple. We can expect Swift to evolve over time, in line with the developments in the Swift Open Source project.

Tip

Xcode supports having multiple versions of the Swift language installed. You might have a different version of the language if, for example, you’ve downloaded a copy of Swift from the open source project. For information on how to get a copy and use it in Xcode, go to the Swift project’s download page.

Swift 3.0 was released in September 2016. This was a very big deal in the Swift community, and the new version included numerous changes to the language as well as to the standard library. At the time of writing, we’re now up to Swift 4.0, released in September 2017. Compared to switching from Swift to Swift 3.0, which had huge amounts of code-breaking changes, moving from Swift 3 to Swift 4.0 is relatively painless, with most of the changes relating to programming quality of life and performance.

Swift draws upon an extensive ...