title: Scaling issue in saving UIImage as NSData
body: <p>I would like to save some image as nsdata into a plist and retrieve it later.
  But I got a problem.</p>
  
  <p>The problem is, if the UIImage with a scale of 2.0, when I load it again later with</p>
  
  <pre><code>[UIImage imageWithData:]
  </code></pre>
  
  <p>the image show 2x size</p>
  
  <p>What I want is to like the behaviour of </p>
  
  <pre><code>[UIImage imageNamed:]
  </code></pre>
  
  <p>which will load according to the screen scale.</p>
  
  <p>How can I do it?</p>