特定のURLの時はブラウザで表示。 ※事前にself.webView.delegate = self;をしておく。

gistfile1.m

- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType {
    if (navigationType == UIWebViewNavigationTypeLinkClicked) {        
        NSString *checkURL = [request.URL absoluteString];
        NSRange linkMatch  = [checkURL  rangeOfString:@"http://example.com"];

        if (linkMatch.location != NSNotFound) {
          [[UIApplication sharedApplication] openURL:request.URL];
            return NO;
        }
    }

    return YES;
}