Swift 2
At the 2014 WWDC conference Apple announced Swift as a new language to write iOS app. In February 2015 they released Swift 1.2, which fixed a lot of issues (especially with the compiler) and added new language features.
In June 2015 Apple announced at WWDC Swift 2, which will be made open source later this year. In this post I will cover the new features in Swift 2.