How to make https calls in Flutter?

I am new to flutter development. I am trying hard to make the https calls work. Whenever I call a https URL, it throws the below error:

SocketException: Failed host lookup: 'someserver.com' (OS Error: nodename nor servname provided, or not known, errno = 8)

Below is the code I am using:

final ioc = new HttpClient();    ioc.badCertificateCallback =        (X509Certificate cert, String host, int port) => true;    final http = new IOClient(ioc);    return http        .post(url, body: body, headers: headers, encoding: encoding)        .then((response) {      final String res = response.body;      final int statusCode = response.statusCode;      if (statusCode < 200 || statusCode > 400 || json == null) {        throw new Exception("Error while posting data");      }      return _decoder.convert(res);    });

I have checked below few links and many more and tried all of them but nothing seems to work.

• How to solve SocketException: Failed host lookup: 'www.xyz.com' (OS Error: No address associated with hostname, errno = 7)
• https://github.com/flutter/flutter/issues/27883

Also please note that I am able to access the server from the browser. Same server is being access from iOS app as well(built using XCode). From iOS I am able to access the server.

Kindly help!