Swift是Apple下一代开发语言，并且为了保证兼容性，Swift代码可以和Objective-C代码共存（官方解释是：New Swift code co-exists along side your existing Objective-C files in the same project）。下面介绍一下它的特性：
- 并行（parallel）：it runs multiple programs concurrently as soon as their inputs are available, reducing the need for complex parallel programming
- 简单（easy）：Short, simple scripts can do large-scale work. The same script runs on multicore computers, clusters, grids, clouds, and supercomputers
- 快（fast）：it can run a million programs, thousands at a time, launching hundreds per second
- 灵活（flexible）：its being used in many fields of science, engineering, and business. Read the case studies