Apple has released the first preview of
Swift 3.0 for download. The primary goal of Swift 3.0 is to solidify and mature the
Swift language and development experience.

Swift 3.0 Preview 1 Snapshots are
prebuilt binaries that are automatically created from swift-3.0-preview-1-branch
branches. These snapshots are not official releases. They have gone through
automated unit testing, but they have not gone through the full testing that is
performed for official releases.
Apple has released the first preview of Swift 3.0 for download. The primary goal of Swift 3.0 is to solidify and mature the Swift language and development experience.
Swift 3.0  can be implemented into
Ubuntu 14.04, 15.10 or directly into Appleā€™s Xcode.
Last month, Apple announced that Swift 3.0 will be released sometime in
late 2016. Swift 3.0 is a major update to Apple’s new programming language. It
contains fundamental changes to the language and Swift Standard Library and is
not source compatible with Swift 2.2.

You can download the first preview for Xcode and Ubuntu from here