UIWebViewHttpStatusCodeHandling_checksession.m

#pragma mark -
#pragma mark UIWebViewDelegate Methods

- (BOOL)           webView:(UIWebView *)webView
shouldStartLoadWithRequest:(NSURLRequest *)request
            navigationType:(UIWebViewNavigationType)navigationType
{
    if (_sessionChecked) {
        [self log:@"session already checked."];
        return YES;
    }

    [self log:@"will check session."];

    NSURLConnection *conn = [NSURLConnection connectionWithRequest:request delegate:self];
    if (conn == nil) {
        NSLog(@"cannot create connection");
    }
    return NO;
}

UIWebViewHttpStatusCodeHandling_handleresponse.m

#pragma mark -
#pragma mark NSURLConnection Data Delegate Methods

- (void) connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    NSLog(@"connection:didReceiveResponse");
    [self log:@"received response."];

    if ([response isKindOfClass:[NSHTTPURLResponse class]]) {
        _sessionChecked = YES;

        NSString *newUrl = @"";
        NSHTTPURLResponse *httpResponse = (NSHTTPURLResponse *) response;
        int status = [httpResponse statusCode];

        if (status == 403) {
            NSLog(@"not authenticated. http status code: %d", status);
            [self log:[NSString stringWithFormat:@"not authenticated. http status code: %d", status]];
            newUrl = [NSString stringWithFormat:
                      @"https://www.google.com/accounts/ServiceLogin?continue=%@", self.url];
        }
        else {
            NSLog(@"authenticated. http status code: %d", status);
            [self log:[NSString stringWithFormat:@"authenticated. http status code: %d", status]];
            newUrl = self.url;
        }

        // cancel the connection. we got what we want from the response,
        // no need to download the response data.
        [connection cancel];

        // start loading the new request in webView
        NSURLRequest *req = [NSURLRequest requestWithURL:[NSURL URLWithString:newUrl]];
        [self.webView loadRequest:req];
    }
}