title: Swift: "Must call a designated initializer of the superclass" error even though code is doing so
body: <p>The goal is to subclass SCNNode. According to the <a href="https://developer.apple.com/library/mac/documentation/SceneKit/Reference/SCNNode_Class/" rel="noreferrer">class docs</a>, <code>init(geometry geometry: SCNGeometry?)</code> is a designated initializer (no <code>convenience</code> keyword listed), so isn't this code invoking a designated initializer of its superclass?</p>
  
  <p>Why is Xcode showing the following error?</p>
  
  <blockquote>
    <p>Must call a designated initializer of the superclass SCNNode</p>
  </blockquote>
  
  <pre><code>class PreviewNode: SCNNode {
      // Constants
      let PreviewNodeColor = gRedColor
      let Size = CGFloat(1.0)
      let ChamferRadius = CGFloat(0.0)
  
      override init() {
          let previewBox = SCNBox(width: Size, height: Size, length: Size, chamferRadius: ChamferRadius)
          previewBox.firstMaterial!.diffuse.contents = PreviewNodeColor
          previewBox.firstMaterial!.transparency = 0.2
          previewBox.firstMaterial!.specular.contents = UIColor.whiteColor()
          super.init(geometry: previewBox)
      }
  }
  </code></pre>