title: Convert a Region latitudeDelta / longitudeDelta into an approximate zoomLevel
body: <p>I use the great <code>react-native-maps</code> from Airbnb on a <code>react-native</code> app.</p>
  
  <p>I got a list of markers on a JSON file where each of these markers have a property <code>zoom</code> which is a integer of an approximate zoom level where the marker should display / hide on the map.</p>
  
  <p>Is there a way based on the <code>latitudeDelta</code> and <code>longitudeDelta</code> of a <code>Region</code> to get an approximate double/integer of the current zoom level as we have on Google Maps (1 to 20) ?</p>
  
  <p>Thanks</p>