php iframe继续在框架内重定向网站

I have an iframe that renders websites (like http://google.com). However for websites that redirect (like http://tinyurl.com/l6llqre), the redirect will open within the entire window of my current browser. How do I fix it so that the website will redirect within the iframe??

Here's my iframe:

public function renderContent() {
  if ($this->url) {
    return
     <iframe
       src={$this->url}
       width="100%"
       height="500px"
       scrolling="no"
     />;
  } else {
    return <ui:box type="red">{'The website cannot be loaded'}</ui:box>;
  }
}

Really new at php, would appreciate any tips!