title: Objective-C - CTFont change font style?
body: <p>I have a CTFont that contains a font style, and sumbolic traits.</p>
  
  <p>I want to create a new font with a new style that inherits the symbolic traits of the first font.
  How can I achieve this?</p>
  
  <pre><code>CTFontRef newFontWithoutTraits = CTFontCreateWithName((CFString)newFontName, CTFontGetSize(font), NULL);
  CTFontRef newFont = CTFontCreateCopyWithSymbolicTraits(newFontWithoutTraits, CTFontGetSize(font), NULL, 0, CTFontGetSymbolicTraits(font));
  </code></pre>
  
  <p>the new font is null here
  I don't know what should I pass to the <code>4th</code> parameter in <code>CTFontCreateCopyWithSymbolicTraits</code>.</p>