The update to Swift makes it the first since the language was open sourced on December 3. It also features contributions from non-Apple employees, but lacks support for Swift Core Libraries on Linux (which is coming in version 3).
In addition to bug fixes and diagnostic enhancements, Swift 2.2 also features tuple comparison operators and Swift language version build configuration. If you want to track the evolution of Swift, there’s a GitHub repository just for you.
Xcode 7.3 brings in interactive playgrounds for all, and a “more intelligent” code completion. Developers can also support multiple Apple Watches for a single iPhone with Xcode 7.3, and the debugger automatically imports the proper framework for Swift and Objective C impressions. Of course, Xcode 7.3 also supports Swift 2.2.