NSURLSessionUploadTask 上传

 -(void)uploadPhotoImageWithUrl:(NSString*)url

                       userIMID:(NSString*)userIMID

                      imageData:(NSData*)imageData

                      imageName:(NSString*)imageName{

     NSString *TWITTERFON_FORM_BOUNDARY = @"AaB03x";

     //根据url初始化request

     NSMutableURLRequest* request = [NSMutableURLRequest requestWithURL:[NSURL URLWithString:url]

                                                            cachePolicy:NSURLRequestReloadIgnoringLocalCacheData

                                                        timeoutInterval:];

     //分界线 --AaB03x

     NSString *MPboundary=[[NSString alloc]initWithFormat:@"--%@",TWITTERFON_FORM_BOUNDARY];

     //结束符 AaB03x--

     NSString *endMPboundary=[[NSString alloc]initWithFormat:@"%@--",MPboundary];

     //http body的字符串

     NSMutableString *body=[[NSMutableString alloc]init];

     //参数的集合的所有key的集合

     if(imageData){

         ////添加分界线，换行

         [body appendFormat:@"%@\r\n",MPboundary];

         //声明pic字段，文件名为boris.png

         [body appendFormat:@"Content-Disposition: form-data; name="%@"; filename="%@"\r\n",userIMID,imageName];

         //声明上传文件的格式

         [body appendFormat:@"Content-Type: image/jpge,image/gif, image/jpeg, image/pjpeg, image/pjpeg\r\n\r\n"];

     }

     //声明结束符：--AaB03x--

     NSString *end=[[NSString alloc]initWithFormat:@"\r\n%@",endMPboundary];

     //声明myRequestData，用来放入http body

     NSMutableData *myRequestData=[NSMutableData data];

     //将body字符串转化为UTF8格式的二进制

     [myRequestData appendData:[body dataUsingEncoding:NSUTF8StringEncoding]];

     if(imageData){

         //将image的data加入

         [myRequestData appendData:imageData];

     }

     //加入结束符--AaB03x--

     [myRequestData appendData:[end dataUsingEncoding:NSUTF8StringEncoding]];

     //设置HTTPHeader中Content-Type的值

     NSString *content=[[NSString alloc]initWithFormat:@"multipart/form-data; boundary=%@",TWITTERFON_FORM_BOUNDARY];

     //设置HTTPHeader

     [request setValue:content

    forHTTPHeaderField:@"Content-Type"];

     //设置Content-Length

     [request setValue:[NSString stringWithFormat:@"%ld", (unsigned long)[myRequestData length]]

    forHTTPHeaderField:@"Content-Length"];

     //设置http body

     [request setHTTPBody:myRequestData];

     //http method

     [request setHTTPMethod:@"POST"];

     // URLSession

     NSURLSession *session = [NSURLSession sharedSession];

     // 上传任务

     NSURLSessionUploadTask *task = [session uploadTaskWithRequest:request

                                                          fromData:myRequestData

                                                 completionHandler:^(NSData *data, NSURLResponse *response, NSError *error)

                                     {

                                         if (!data) {

                                             NSString *result = [[NSString alloc] initWithData:data

                                                                                      encoding:NSUTF8StringEncoding];

                                             NSLog(@"%@ %@", result, response);

                                         } else {

                                             NSString *result = [[NSString alloc] initWithData:data

                                                                                      encoding:NSUTF8StringEncoding];

                                             NSLog(@"upload ok!  %@ ", result);

                                         }

                                     }];

     [task resume];

 }