title: how to locate objects in SCNNode object boundingBox for show/hide feature
body: <p>Having an issue getting a function to work when trying to setup boundingBox detection in a SCNNode. I'm expecting to be able to call the boundingBox function to detect objects inside a SCNNode and hide/show those objects on a button tap, here is my current state below:</p>
  
  <pre><code> @IBAction func hideCubeButtonTapped(sender: UIButton) {
      guard let hatNode = hatNode?.presentation.worldPosition else { return }
  
  
      for cubeNode in cubeNodes {
  
  
          // hide/show cubeNodes in the hat
          if (hatNode.boundingBoxContains(point: cubeNode.presentation.worldPosition)) {
              print("Hide Button Tapped")
              if cubeNode.isHidden == true {
                  cubeNode.isHidden = false
              } else {
                  cubeNode.isHidden = true
              }
          }
      }
  }
  </code></pre>
  
  <p>which is calling the boundingBox function from this struct and extension:</p>
  
  <pre><code>extension SCNNode {
  func boundingBoxContains(point: SCNVector3, in node: SCNNode) -&gt; Bool {
      let localPoint = self.convertPosition(point, from: node)
      return boundingBoxContains(point: localPoint)
  }
  
  func boundingBoxContains(point: SCNVector3) -&gt; Bool {
      return BoundingBox(self.boundingBox).contains(point)
  }
  </code></pre>
  
  <p>}</p>
  
  <p>struct BoundingBox {
      let min: SCNVector3
      let max: SCNVector3</p>
  
  <pre><code>init(_ boundTuple: (min: SCNVector3, max: SCNVector3)) {
      min = boundTuple.min
      max = boundTuple.max
  }
  
  func contains(_ point: SCNVector3) -&gt; Bool {
      let contains =
          min.x &lt;= point.x &amp;&amp;
              min.y &lt;= point.y &amp;&amp;
              min.z &lt;= point.z &amp;&amp;
  
              max.x &gt; point.x &amp;&amp;
              max.y &gt; point.y &amp;&amp;
              max.z &gt; point.z
  
      return contains
  }
  </code></pre>
  
  <p>}</p>
  
  <p>when calling the hatNode.boundingBoxContains this error is showing:
  "Value of type 'SCNVector3' has no member 'boundingBoxContains'"</p>
  
  <p>the hatNode is not getting set as a SCNVector3? what am i missing here? i'm new to swift so please correct me here!</p>
  
  <p>this code was adapted from this question:
  <a href="https://stackoverflow.com/questions/47149669/how-to-detect-if-a-specific-scnnode-is-located-inside-another-scnnodes-bounding">How to detect if a specific SCNNode is located inside another SCNNode&#39;s boundingBox - SceneKit - iOS</a></p>