title: react-native-router-flux - trigger function on specific route load
body: <p>I am trying to trigger a function whenever a specific route within a router loads. I am using react-native-router-flux 2.x and ReactNative 0.21 (Can't update to 3.x right now).</p>
  
  <p>For example below I just want to trigger a function whenever screen2 is loaded. Is this possible? I tried using onPush but it didn't seem to work.</p>
  
  <p>The reason I need this is because I cannot use componentDidMount, componentWillMount for the screen2 component as it will only load the first time the component is called. I need a function to trigger every time the route is selected. Thanks!</p>
  
  <pre><code>  &lt;Route name="screen1" initial={!needSignIn}&gt;
      &lt;Router footer={TabBar} hideNavBar={true} &gt;
        &lt;Route name="screen1" hideNavBar={true} title="Screen1" schema="tab" component={Screen1} /&gt;
        &lt;Route onPush={()=&gt;{console.log("onPush is called!");}} name="screen2" hideNavBar={true} title="Screen2" schema="tab" component={Screen2} /&gt;
        &lt;Route name="screen3" hideNavBar={true} title="Screen2" schema="tab" component={Screen3} /&gt;
      &lt;/Router&gt;
    &lt;/Route&gt;
  </code></pre>