title: Convert UIFont to CTFontRef and add italic on Retina display
body: <p>I have a custom subclass of <code>UILabel</code> which makes custom drawing using CoreText.
  I used to draw my strings using the <code>UIFont</code> that is set on the label accessing it using the font property. I also add some traits to the font. Here is what it looks like:</p>
  
  <pre><code>UIFont* font = [self font];
  CTFontRef ref = CTFontCreateWithName((CFStringRef)[font name], [font pointSize], NULL);
  CTFontRef italicFont = CTFontCreateCopyWithSymbolicTraits(ref, [font pointSize], NULL, kCTFontItalicTrait, kCTFontItalicTrait);
  </code></pre>
  
  <p>This used to work fine until the new ipad appeared with its retina display. When I perform the <code>CTFontCreateCopyWithSymbolicTraits</code> call, it produces a nil return value. I found out <code>[font name]</code> returns ".HelveticaNeueUI" on these new devices. The <code>CTFontCreateWithName</code> seems to work fine with this private font name, but <code>CTFontCreateCopyWithSymbolicTraits</code> doesn't. Yet if I create an italic font using <code>[UIFont italicSystemFontOfSize:[font pointSize]]</code> it creates an italic font for which <code>[font name]</code> still returns ".HelveticaNeueUI".</p>
  
  <p>How should I convert my <code>UIFont</code> to <code>CTFontRef</code> so that I can still apply new traits to my <code>CTFontRef</code> on both retina and non-retina displays?</p>