http://geek.csdn.net/news/detail/100195
https://developer.apple.com/library/content/samplecode/UnicornChat/Introduction/Intro.html#//apple_ref/doc/uid/TP40017332
http://www.cnblogs.com/yaoxc/p/4029606.html
原文：http://www.cnblogs.com/qiutangfengmian/p/7259079.html