title: Zoom In/Out react-native-maps based on radius in km/miles
body: <p>I have a requirement in my react-native app where in which if the user provides a number which will be the number of kilometres or miles (like 5 or 10), the map should zoom in/out showing the area with radius as the input number.</p>
  <p>How can I change the latitudeDelta and longitudeDelta values based on those input numbers.</p>
  <p>Please help me out. Thanks in advance.</p>