title: centering text in a UILabel with an NSAttributedString
body: <p>Going through some basic improvements to a application I am working on. Still new to the iOS swift development scene. I figured that the lines of text in my code would automatically be centered because I set the label to center. After a little bit of research I discovered this is not the case. How would I align code like this to center:</p>
  
  <pre><code>let atrString = try NSAttributedString(
     data: assetDetails!.cardDescription.dataUsingEncoding(NSUTF8StringEncoding)!, 
     options: [NSDocumentTypeDocumentAttribute:NSHTMLTextDocumentType], 
     documentAttributes: nil)
  assetDescription.attributedText = atrString
  </code></pre>