title: React-Native-Maps fits Coordinate right after being loaded
body: <p>The example provided in the examples of the react-native-maps repo on GitHub shows a button to execute a function to set the appropriate zoom considering to a list of markers:</p>
  
  <pre><code>  fitAllMarkers() {
      this.map.fitToCoordinates(MARKERS, {
        edgePadding: DEFAULT_PADDING,
        animated: true,
      });
  }
  </code></pre>
  
  <p><a href="https://github.com/airbnb/react-native-maps/blob/master/docs/mapview.md" rel="noreferrer">https://github.com/airbnb/react-native-maps/blob/master/docs/mapview.md</a></p>
  
  <p>Would it be possible to initialize the map with the appropriate fit given an array of markers already initialized ?</p>
  
  <p>When trying to set the right fit on the <code>componentDidMount</code>, I am receiving:</p>
  
  <p><code>Error using new LatLntBounds(LatLngBounds, int): Map size can't be 0. Most likely, layout has not yet occured for the map view</code>.</p>
  
  <p>It is definitively too early to call my <code>fitAllMarkers()</code> function. 
  Is there a <code>onLoad</code> function that can be triggered right after the map was initialized ?</p>