NSURLSession网络相关

1.构成
NSURLSession
NSURLSessionConfiguration
NSURLSessionTask -task.taskIdentifier
NSURLSessionDataTask
2.代理
2.1NSURLSessionTaskDelegate

• (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didReceiveChallenge:(NSURLAuthenticationChallenge *)challenge completionHandler:(void (^)(NSURLSessionAuthChallengeDisposition disposition, NSURLCredential *credential))completionHandler ;

• (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error ;

2.2NSURLSessionDataDelegate

• (void)URLSession:(NSURLSession *)session
  dataTask:(NSURLSessionDataTask *)dataTask
  didReceiveResponse:(NSURLResponse *)response
  completionHandler:(void (^)(NSURLSessionResponseDisposition disposition))completionHandler ；

• (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data;

• (void)URLSession:(NSURLSession *)session
  dataTask:(NSURLSessionDataTask *)dataTask
  willCacheResponse:(NSCachedURLResponse *)proposedResponse
  completionHandler:(void (^)(NSCachedURLResponse *cachedResponse))completionHandler ;