title: Swift: Default value for properties in Protocol
body: <p>I am trying to provide a default value for a variable in a Protocol.  I am getting an error: </p>
  
  <p><code>Type ViewController does not conform to protocol Test</code></p>
  
  <p>Code:</p>
  
  <pre><code>protocol Test {
      var aValue: CGFloat { get set }
  }
  
  extension Test {
      var aValue: CGFloat {
          return 0.3
      }
  }
  
  
  class ViewController: UIViewController, Test {
  
      override func viewDidLoad() {
         super.viewDidLoad()
         print("value \(aValue)")
      }
  }
  </code></pre>
  
  <p>How can I provide a default value so the <code>ViewController</code> can use the default value (in the protocol extension) without to declaring it?</p>