title: Change TextInput Style on Focus React Native
body: <p>First of all, I've researched through other posts and find this <a href="https://stackoverflow.com/questions/35581548/how-to-change-styling-of-textinput-placeholder-in-react-native/39764112">How to change styling of TextInput placeholder in React Native?</a></p>
  
  <p>The issue with the solutions in the post is once <code>fontStyle</code> is set to italic, it won't go back to normal font (I'm guessing that it can't be overridden unless the component updates). Here is my code sample</p>
  
  <pre><code>  &lt;TextInput
      style={
        this.state.value.length === 0
        ? {fontStyle: 'italic', color: 'white'} // font changed to white and italic
        : {fontStyle: 'normal', color: 'black'} // font changed to black but stays italic
      }
      value={this.state.value}
    /&gt;
  </code></pre>
  
  <p>I came up with some hack by forcing the <code>TextInput</code> to update using <code>forceUpdate()</code> or set a key to the component, but this caused the keyboard UI to close when user is typing which is bad for UX.</p>
  
  <p>I'd like to simply comment on the linked post instead but my reputation is not enough.</p>
  
  <p>Is that intended behavior or did I make any mistake?
  If anyone can provide some explanation / solution, it will be greatly appreciated.</p>
  
  <p>P.S. Tested on Android using the latest React Native</p>