title: Get size of a View in React Native
body: <p>Is it possible to get the size (width and height) of a certain view? For example, I have a view showing the progress:</p>
  
  <pre><code>&lt;View ref='progressBar' style={{backgroundColor:'red',flex:this.state.progress}} /&gt; 
  </code></pre>
  
  <p>I need to know the actual width of the view to align other views properly. Is this possible?</p>