关于 ios post 方式上传 文件的问题

- (IBAction)commitData:(UIButton *)sender {

    

    

    //分界线的标识符

    NSString *TWITTERFON_FORM_BOUNDARY =@"AaB03x";

    //根据url初始化request

    NSMutableURLRequest* request = [NSMutableURLRequestrequestWithURL:[NSURLURLWithString:@"http://192.168.15.66/Cn66law_Biz.Host.Wapi/api/LawChat/UploadTask"]];

    //分界线 --AaB03x

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

    //结束符 AaB03x--

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

    

    //http body的字符串

    NSMutableString *body=[[NSMutableStringalloc]init];

    

    NSData *imgData=UIImageJPEGRepresentation(self.imageView.image,0.5);

    NSMutableDictionary *params = [NSMutableDictionarydictionary];

    

    params[@"tag"] =@1;

    

    //参数的集合的所有key的集合

    NSArray *keys= [paramsallKeys];

    

    //遍历keys

    for(int i=0;i<[keyscount];i++)

    {

        //得到当前key

        NSString *key=[keysobjectAtIndex:i];

        //如果key不是pic，说明value是字符类型，比如name：Boris

        if(![keyisEqualToString:@"pic"])

        {

            //添加分界线，换行

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

            //添加字段名称，换2行

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

            //添加字段的值

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

        }

    }

    

    ////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=\"pic\"; filename=\"boris.png\"\r\n"];

    //声明上传文件的格式

    [body appendFormat:@"Content-Type: image/png\r\n\r\n"];

    

    //声明结束符：--AaB03x--

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

    //声明myRequestData，用来放入http body

    NSMutableData *myRequestData=[NSMutableDatadata];

    //将body字符串转化为UTF8格式的二进制

    [myRequestData appendData:[bodydataUsingEncoding:NSUTF8StringEncoding]];

    //将image的data加入

    [myRequestData appendData:imgData];

    //加入结束符--AaB03x--

    [myRequestData appendData:[enddataUsingEncoding:NSUTF8StringEncoding]];

    

    //设置HTTPHeader中Content-Type的值

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

    //设置HTTPHeader

    [request setValue:contentforHTTPHeaderField:@"Content-Type"];

    //设置Content-Length

    [request setValue:[NSStringstringWithFormat:@"%lu", (unsignedlong)[myRequestData length]]forHTTPHeaderField:@"Content-Length"];

    //设置http body

    [request setHTTPBody:myRequestData];

    //http method

    [request setHTTPMethod:@"POST"];

    

    NSOperationQueue *queue=[[NSOperationQueuealloc] init];

    [NSURLConnectionsendAsynchronousRequest:request queue:queue

                           completionHandler:^(NSURLResponse *respone,

                                               NSData *data,

                                               NSError *error)

     {

         if ([datalength]>0 && error==nil) {

             NSString *jsonstring=[[NSStringalloc] initWithData:dataencoding:NSUTF8StringEncoding];

             //[self.respondTextView setText:jsonstring];

             NSLog(@"data:%@",jsonstring);

             //[self performSelectorOnMainThread:@selector(setRespondtext:)withObject:jsonstring waitUntilDone:YES modes:nil];

             //[self performSelectorOnMainThread:@selector(setRespondtext:) withObject:data waitUntilDone:NO];

         }

     }

     ];

}