iOS 8 引入WKWebView, WKWebView 不支持JavaScriptCore的方式但提供message handler的方式为JavaScript 与Objective-C 通信.

 参考：

http://www.jianshu.com/p/9513d101e582

http://www.cnblogs.com/jiang-xiao-yan/p/5345893.html

http://www.jianshu.com/p/939db6215436

http://blog.csdn.net/reylen/article/details/46445509

http://www.cnblogs.com/jiang-xiao-yan/p/5345893.html

http://mp.weixin.qq.com/s?__biz=MzIzMzA4NjA5Mw==&mid=214063688&idx=1&sn=903258ec2d3ae431b4d9ee55cb59ed89#rd

http://www.jianshu.com/p/939db6215436

http://www.cnblogs.com/oc-bowen/p/6092730.html

http://www.jianshu.com/p/84a6b1ac974a

WKWebView与JS交互