title: How to override Objective-c class functions in Swift?
body: <p>I'm currently trying to override the systemFontOfSize method of UIFont to return my custom font with the given font size. My code currently looks like this:</p>
  
  <pre><code>extension UIFont
  {
      class func systemFontOfSize(fontSize: CGFloat) -&gt; UIFont
      {
          return UIFont(name: "HelveticaNeue", size: 10)!
      }
  }
  </code></pre>
  
  <p>However, I am unable to override that method. When using the code shown above, I get the following error:</p>
  
  <pre><code>"Method 'systemFontOfSize' with Objective-C selector 'systemFontOfSize:' conflicts with previous declaration with the same Objective-C selector"
  </code></pre>
  
  <p>When adding override, the error is that the method is not overriding anything. 
  Does anyone know how to fix this issue?</p>