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