一些reactiveCocoa资料:
http://www.raywenderlich.com/62699/reactivecocoa-tutorial-pt1
http://www.raywenderlich.com/62796/reactivecocoa-tutorial-pt2
http://www.raywenderlich.com/55384/ios-7-best-practices-part-1
http://www.raywenderlich.com/55384/ios-7-best-practices-part-1
http://www.raywenderlich.com/70598/reactivecocoa-tech-talk-video