For a GET request I\'ve tried this simple method:
NSString *urlAddress = @"http://example.com/";
NSURL *url = [NSURL URLWithString:urlAddress];
NSURLReq
You can use something like ASIHTTPRequest to make the POST request (With the option of doing it asynchronously) and then load the response string/data into the UIWebView. Look at this page under the section titled Sending data with POST or PUT requests and then look at the Creating an asynchronous request section at the top for information on how to handle the response string/data.
Hope that helps, sorry if I misunderstood your question.