title: Method cannot be declared, internal type
body: <p>I have a delegate here and I'm getting the following error:</p>
  
  <blockquote>
    <p>'method cannot be declared public because its parameter uses an internal type'</p>
  </blockquote>
  
  <p>Here is the code. </p>
  
  <pre><code>public protocol CaptureViewControllerDelegate: class {
      /**
       Called when the `controller` captures an image.
       */
      // "error is here" func captureViewController(_ controller: ViewController, didCaptureStillImage image: UIImage?)
  }
  </code></pre>