title: pngData back to UIImage
body: <p>I have a <code>UIImage</code> variable, <code>a</code>. I would like to use it within my app as a .png data file. How do I go about recasting <code>a</code> back into a <code>UIImage</code> for use? </p>
  
  <p>How can I cast this data object back into a <code>UIImage</code>?</p>
  
  <pre><code>let pngImage = a!.pngData()
  </code></pre>