title: Update the Marker position on Maps on a new position change - React native
body: <p>I have initialized a react native map with an initial region co-ordinate. </p>
  
  <pre><code> &lt;MapView
       style={{ ...styles.map, marginTop: this.state.marginTop }}
       initialRegion={this.state.region}
       showsUserLocation={true}
       followsUserLocation={true}
       onMapReady={this.onMapReady}
       onRegionChangeComplete={this.onRegionChange}         
       &gt;
       &lt;MapView.Marker
       coordinate={this.state.region}
       title={"Your location"}
       draggable                  
       /&gt;
   &lt;/MapView&gt;
  </code></pre>
  
  <p>Now fetching a new location from the server, which has a new latitude and longitude, which I want to display as a new marker on my maps. I have updated the region with new latitude and longitude on ononRegionChange. </p>
  
  <p>But I'm unable to invoke the new marker position on the region change. Can anyone help me out here?</p>