Apple has delivered on its promise to make its Swift programming language open source by offering it under the Apache License. The Swift team has gone ahead and uploaded the source code for the Swift compiler along with the standard library functions and objects.
This move could cause a big boost in popularity for Apple's programming language as it will enable Swift to expand beyond iOS and Mac OS X. Developers now have the freedom to use Swift on a variety of different platforms including Windows. Hopefully this will encourage the developer community to embrace Apple's programming language and to help improve it.
It will be interesting to see the way in which Apple handles its transition from a proprietary programming language to an open source one. Developers may want to make big changes to Swift which could lead to disagreements with Apple. On Swift's website, the team behind the programming language states that they prefer small incremental improvements.
Developers were quite surprised when Apple decided to release parts of the Swift Foundation in addition to the code for the raw language compiler and standard library. The AppKit and UIKit framework will continue being exclusive to Mac and iOS app development though. The core libraries made available do contain a few key components from both of these frameworks including a networking stack, threading and common data types.
Swift's source code is being hosted on a GitHub repository and many of the features Apple is including alongside it are planned features for Swift 3.0.