KZPlayground 是 Objective-C Playgrounds，特性：
比 Swift playgrounds 快很多
Extra controls for tweaking:
Adjustable values
Auto-animated values
Buttons
IDE agnostic, once you run it, you can modify the code even from vim.
Full iOS simulator and access to all iOS features, so you can prototype production ready code.
Nice DSL for rapid prototyping
CocoaPods support, so you can add it to existing projects to experiment
Open source, anyone can contribute to make them better!
