RACSignal底层分析

http://nshipster.cn/reactivecocoa/
http://yulingtianxia.com/blog/2014/07/29/reactivecocoa/#%E4%BC%98%E7%A7%80%E6%96%87%E7%AB%A0
http://www.infoq.com/cn/articles/reactivecocoa-ios-new-develop-framework
mvvm: http://www.infoq.com/cn/articles/mvvm-revelation/

http://benbeng.leanote.com/post/ReactiveCocoaTutorial-part1
http://tech.meituan.com/tag/ReactiveCocoa
http://blog.devtang.com/2016/01/03/reactive-cocoa-discussion/

http://blog.csdn.net/huangjijie123456/article/details/49837231

http://www.cocoachina.com/ios/20150526/11930.html

http://www.cnblogs.com/ludashi/p/4925042.html

https://my.oschina.net/EasyIOS/blog/294178

demo:
https://github.com/AshFurrow/C-41
https://github.com/jspahrsummers/GroceryList
https://github.com/leichunfeng/MVVMReactiveCocoa/releases