title: How can add shadow of tab bar in react-navigation-material-bottom-tabs?
body: <p>I am using react-navigation &amp; react-navigation-material-bottom-tabs in react-native to create bottom tab-bar. And I am trying to add shadow effect for bottom tab bar.</p>
  
  <p>My Code for generating shadow is:</p>
  
  <pre><code>    const screen1 = createMaterialBottomTabNavigator(
          {
              Home: HomeScreen,
              About: AboutScreen,
              Scan: ScanScreen,
              Fav: AllScreen
          },
          {
              initialRouteName: "Home",
              activeColor: 'red',
              inactiveColor: 'blue',
  
              barStyle: {
                  borderWidth: 0.5,
                  borderBottomWidth: 1,
                  backgroundColor: 'white',
                  borderBottomLeftRadius: 0,
                  borderBottomRightRadius: 0,
                  borderTopLeftRadius: 15,
                  borderTopRightRadius: 15,
                  borderTopColor: '#000',
                  borderBottomColor: '#000',
                  borderLeftColor: '#000',
                  borderRightColor: '#000',
                  shadowColor: "#000000",
                  shadowOpacity: 1,
                  shadowRadius: 30,
                  shadowOffset: {
                      height: 10,
                      width: 10
                  },
                  elevation: 5
              },
          }
      );
  
  </code></pre>
  
  <p>But shadow effects are not shown in both IOS &amp; Android.</p>