Swift: "Must call a designated initializer of the superclass" error even though code is doing so
<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>