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.
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 the link below...