<NSURLSessionTaskDelegate>
1.部分回调函数通过task.taskIdentifier获取到AFURLSessionManagerTaskDelegate调用2.deleagte方法都有相应的Block3.完成，挂起，恢复，错误 post通知
<AFMultipartFormData>
AFHTTPRequestSerializer <AFURLRequestSerialization>
<AFURLResponseSerialization>
AFJSONRequestSerializer
<NSURLSessionDataDelegate>
AFURLSessionManager
<AFURLRequestSerialization>
AFXMLDocumentResponseSerializer
AFHTTPResponseSerializer
<NSURLSessionDownloadDelegate>
AFXMLParserResponseSerializer
AFImageResponseSerializer
AFSecurityPolicy
@dynamic
AFPropertyListResponseSerializer
AFHTTPSessionManager
GET/POST/DELETE/PUT
AFNetworkReachabilityManager
AFPropertyListRequestSerializer
SessionDelegate
AFHTTPResponseSerializer <AFURLResponseSerialization>
<NSURLSessionDelegate>
AFHTTPRequestSerializer
AFURLSessionManagerTaskDelegate
