Swift is a programming language for iOS and OS X development created by Apple. Designed to coexist with Objective-C and to be more resilient against erroneous code, Swift was introduced in 2014 at Apple’s developer conference WWDC. It is built with the LLVM compiler included in Xcode 6+.

The official Swift Programming Language book from Apple is now available via iBooks. It goes into much more detail than this guide, and if you have the time and patience to read it, it’s recommended. Some of these examples are from that book.

Another great reference is About Swift on Swift’s website.