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];

 }