title: UIProgressView and Custom Track and Progress Images (iOS 5 properties)
body: <p>I am experimenting with some new properties in iOS 5 regarding <code>UIProgressView</code>. They are:</p>
  
  <p><code>@property(nonatomic, retain) UIImage *progressImage;</code><br>
  <code>@property(nonatomic, retain) UIImage *trackImage;</code></p>
  
  <p>These new properties enable the customisation of the "<em>progress</em>" and the "<em>track</em>" image, so that you can make fancy progress bars without having to roll-your-own.</p>
  
  <p>I however cannot understand how Apple "<em>stretches</em>" the progress images, because documentation is a little flakey / OR there is some standard I am not aware of. <strong>Regardless, I am asking if someone can help me understand how to make appropriate progress and tracking images.</strong></p>
  
  <p>I get results like this when I load my custom images, no matter which sizes I try:</p>
  
  <p><img src="https://i.stack.imgur.com/6f10H.png" alt="Progress Example"></p>
  
  <p>My measurements are as follows:</p>
  
  <ul>
  <li>UIProgressView length: 226 units</li>
  <li>trackingImage.png: 10px</li>
  <li>progressImage.png: 7px</li>
  </ul>
  
  <p>Lastly, here are my custom images:</p>
  
  <p><img src="https://i.stack.imgur.com/r83Lu.png" alt="The Progress Image"> <code>progressImage.png</code></p>
  
  <p><img src="https://i.stack.imgur.com/feCkH.png" alt="The Tracking Image"> <code>trackImage.png</code></p>