httpwebrequest xcode exc_bad_access

I'm using the google weather api in the C# script and it runs correctly in Unity. The problem is when I build and run it with xcode it gives the following error GDB: Program received signal: "EXC_BAD_ACCESS". And the Unity program won't run. The error comes from the http web request in the code below.

     GWP_Request = (HttpWebRequest)WebRequest.Create(string.Format(baseUrl));
     GWP_Request.UserAgent = @"Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.8.1.4) Gecko/20070515 Firefox/2.0.0.4";
     GWP_Response = (HttpWebResponse)GWP_Request.GetResponse();
     GWP_XMLdoc = new XmlDocument();
     GWP_XMLdoc.Load(GWP_Response.GetResponseStream());

How should I change the web request so it works with xcode?