Today, Apple announced that Swift 2 is on its way with a number of new features and better performance. But perhaps the most striking news is that the whole codebase—the compiler and standard libraries—will be open sourced. Code that even works on Linux will be released later this year.

Apple VP Craig Federighi dropped the news about Swift as what seemed like an afterthought following a long description of MacOS and iOS features and enhancements . He said that Apple would be "stepping on the gas this year with Swift 2," and he promised significant speedups to the performance of applications coded with the language. Part of this comes from what he termed "whole module optimization," although he offered no details as to what that entailed.

Most of the details came from a single slide, which showed some of the new features behind a Swift logo. Key among these were an error handling system, something that was notably missing in the original release. Developers will also appreciate much shorter compile times. But for most of the details, we'll have to wait for some of the sessions on the language, which will come later today.