UIWebView get http status code from loaded page

I using a UIWebView in a game to display a customer support form. I noticed i have problem to close the webview if the server return a 503 error (http status code sent from a load balancer)

Is there a way to easily get this http status ? can I do some setup in order to get the didFailWithError called when the http status code is not 200 ?

loading code

UIWebView *webView = [[UIWebView alloc] initWithFrame:self.view.frame];

NSURL *nsURL = [NSURL URLWithString:url];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:nsURL];

webView.opaque = YES;

webView.userInteractionEnabled = YES;

[webView loadRequest:request];

webView.delegate = self;

closableWebViewController = [[UIViewController alloc] init];

[closableWebViewController.view setFrame:self.view.frame];

[closableWebViewController.view addSubview:webView];

[self presentViewController:closableWebViewController animated:YES completion:nil];

this delegate method is not called

-(void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error
{
 NSLog(@"webview error %@",error);

 if (closableWebViewController)
 {
    NSLog(@"closing webview");
    [closableWebViewController dismissViewControllerAnimated:TRUE completion:^{
        closableWebViewController = nil;
        NSLog(@"webView closed");
    }];

 }
}