title: React Native on goBack from SPECIFIC screen call a function refresh
body: <p>I found similar questions but none answered it the way I need.</p>
  <p>I use react navigation. I have two screens, HomeScreen and PostScreen. When I create a post in PostScreen I use</p>
  <pre><code>this.props.navigation.goBack()
  </code></pre>
  <p>and successfully go back to home screen, however inside HomeScreen I have a certain function called <code>refresh()</code> and I would love for that function to be called upon using goBack from PostScreen. Solutions on similar questions show how to refresh screen ,from goBack but anytime coming from ANY screen by using stuff like <code>onWillFocus()</code> or some listeners, but I want this behaviour to only be for specific screen. I guess I need to pass some stuff don't I? I use class components btw.</p>
  <p>SO BASICALLY I NEED:
  onWillFocus { this.refresh() IF I CAME FROM POSTSCREEN and not if I came from anywhere}</p>