Apple released Swift 1.2 beta as part of Xcode 6.3 beta with improvements to the Swift compiler and new features in the Swift language. The compiler enhancements improve stability and performance with faster incremental builds and executables as well as better diagnostics. New features in Swift include the ability of functions to return multiple values, closures that can capture values, enhanced enums that support initializers and extensions, and generics for flexible and reusable code. Additional features are more powerful optional unwrapping, a native Set data structure, and ability to express nullability in Objective-C headers.