使用带网关保护的JSON Webservice时，在IOS中没有响应

下面的代码是简单的登录应用程序。我使用Post请求传递用户名和密码以获取详细信息。但我从web服务得到@“”响应

email= emailTextField.text;
password=passwordTextfield.text;

NSString *post = [[NSString alloc] initWithFormat:@"UserName=%@&Password=%@",email,password];

NSData *postData = [post dataUsingEncoding:NSUTF8StringEncoding allowLossyConversion:YES];

NSString *postLength = [NSString stringWithFormat:@"%d", [postData length]];

NSURL *url = [NSURL URLWithString:@"http:Gateway/api/json"];
NSMutableURLRequest *theRequest = [NSMutableURLRequest requestWithURL:url];
[theRequest setHTTPMethod:@"POST"];
[theRequest setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];
[theRequest setValue:postLength forHTTPHeaderField:@"Content-Length"];
[theRequest setHTTPBody:postData];
[theRequest setHTTPBody:postData];

NSURLResponse *response;// = [[NSURLResponse alloc] init];

NSError *error;// = [[NSError alloc] init;

NSData *urlData = [NSURLConnection sendSynchronousRequest:theRequest returningResponse:&response error:&error];

NSString *str=[[NSString alloc]initWithData:urlData encoding:NSUTF8StringEncoding];

NSLog(@"Login response: is %@",str);

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要向服务器提供身份验证凭据，请使用NSURLConnection委托

- (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge {

    if ([challenge previousFailureCount] == 0) {

        NSURLCredential *credential;
        credential = [NSURLCredential credentialWithUser:userName password:password persistence:NSURLCredentialPersistenceNone];
        [[challenge sender] useCredential:credential forAuthenticationChallenge:challenge];
    } else {
        [[challenge sender] cancelAuthenticationChallenge:challenge];
    }
}

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查看提供身份验证的方法。我应该调用哪种方法来传递用户名和密码凭据？NSLog（@“errot:%@”，error）；这是获取操作无法完成的错误。（NSURErrorDomain错误-1012。）“用户信息=0xa219390{NSErrorFailingURLKey=http://1，NSERRORFAILINGURSTRINGKEY=http:///api/json/reply/Customer/?，NSUnderlyingError=0x8f3e3c0“该操作无法完成。（KCFerrorDomainCFN网络错误-1012）。”