Adding SceneKit Camera node vanishes my main node
<p>I am just starting off with SceneKit and I have some code that renders a cube onto the screen.  It shows up find but as soon as I add a camera node the cube no longer appears on screen.  Given that I'd set the position of the cube's Node to 0,0,0 and the same for the camera, I cannot figure out what is wrong.  I attempted to set the <code>pointOfView</code> property of the <code>SCNView</code> to the camera node but this did not work.  </p>

<p>Here is the code for clarification:</p>

<pre><code>func setup() {

      box = SCNBox(width: 30, height: 30, length: 30, chamferRadius: 5)
      shapeNode.geometry = box
      shapeNode.position = SCNVector3(x:0, y:0, z:0)

      mainNode.addChildNode(shapeNode)

      scene.rootNode.addChildNode(mainNode)

      sceneKitView = SCNView(frame:bounds, options:nil)
      sceneKitView.autoenablesDefaultLighting = true
      sceneKitView.allowsCameraControl = true
      sceneKitView.scene = scene
      sceneKitView.backgroundColor = UIColor.blackColor()
      addSubview(sceneKitView)

     //      cameraNode.camera = SCNCamera()
     //      cameraNode.position = SCNVector3Make(0, 0, 10)
     //      scene.rootNode.addChildNode(cameraNode)
     //      sceneKitView.pointOfView = cameraNode

}
</code></pre>