The examples fron this page came from Apple's Offical Swift Book The Swift Programming Language (Swift 2.1). Theblog post on my personal blog and the source code avaliable on github follows the WFTPL License
Swift 2.1 Xcode 7.1
##Author Jerry Fengwei Zhang(zhang96), codingjerry@gmail.com.
Download as a zip, unzip it and open the plagrounnd file using latest Xcode.
Its free of use under WTFPL license, please read the license file.