https://github.com/AFNetworking/AFNetworking/
http://blog.csdn.net/duxinfeng2010/article/details/8620901
http://www.raywenderlich.com/zh-hans/36079/afnetworking%E9%80%9F%E6%88%90%E6%95%99%E7%A8%8B%EF%BC%881%EF%BC%89
原文：http://www.cnblogs.com/viste/p/3809072.html