title: How to update components in React Native when user leaves the app with Home or Overview buttons?
body: <p>Using React on the web, it's easy to estimate when a component mounts or unmounts because of how users visit/leave certain routes.</p>
  
  <p>If I want to fetch some data on page load and display a component dynamically with that data, I'd do something like:</p>
  
  <pre><code>componentWillMount() {
      this.props.fetchData();
  }
  </code></pre>
  
  <p>If they exit this page and come back later, I know that they're back so I can mount and display some fresh data.</p>
  
  <p>However, working with React-Native for Android, there's something I don't understand. When a user leaves the app via pressing the Home button or the Overview button, the component they left behind does not unmount. So if they come back to the app, the component won't get mounted (it's mounted already) and because of this, the data displayed won't be refreshed.</p>
  
  <p>If the user leaves the app with the Back button, it's good news because then the component will unmount so when they come back, the example fetchData function will fire again.</p>
  
  <p>What's the general practice when it comes to tracking user behavior with Home and Overview buttons?</p>