title: Change color of TouchableOpacity in React Native
body: <p>Can anyone help me. 
  This is my source code: <a href="https://snack.expo.io/rJFgyPDpH" rel="nofollow noreferrer">https://snack.expo.io/rJFgyPDpH</a></p>
  
  <p>Idea is that, if I click to "<strong>1 Button</strong>" it should be 'red' and if I click to <strong>"2 Button"</strong> is also should change its color to 'red' but the <strong>"1 Button"</strong> should be changed to its default colour which is black. However, <strong>"2 Button"</strong>. </p>
  
  <p>If my approach is too simple, other methods (such as <code>TouchableHighlight</code>, ES6 and etc) are also welcomed. I appreciate if you show me mistakes so that I learn from that.</p>