Swift is a new programming language for iOS and OS X apps that builds on the best of C and Objective-C, without the constraints of C compatibility.

Swift adopts safe programming patterns and adds modern features to make programming easier, more flexible and more fun.

Swift’s clean slate, backed by the mature and much-loved Cocoa and Cocoa Touch frameworks, is an opportunity to imagine how software development works.

Swift is the first industrial-quality systems programming language that is as expressive and enjoyable as a scripting language.

简单的说：

1. Swift 用来写 iOS 和 OS X 程序。
2. Swift 吸取了C和 Objective-C 的优点，且更加强大易用。
3. Swift 可以使用现有的 Cocoa 和 Cocoa Touch 框架。
4. Swift 兼具编译语言的高性能（Performance）和脚本语言的交互性（Interactive）。