title: swift how to use enum in extension
body: <p>how to add some type of CAMediaTimingFunction in CALayer  with extension</p>
  
  <pre><code>extension CALayer{
          enum easings {
             case easeIn01
             case easeOut01
          }
  
  
          var ease: easings{
             switch self.ease {
             case .easeIn01:
               return (CAMediaTimingFunction(controlPoints: 0.47, 0, 0.745, 0.715))
             case .easeOut01:
                return (CAMediaTimingFunction(controlPoints: 0.39, 0.575, 0.565, 1))
             }
          }
      }
  </code></pre>