title: Find out when SCNNode disappears from SCNScene
body: <p>Does a particular method get called when an SCNNode is removed from the scene?</p>
  
  <p>-(void)removeFromParentNode;</p>
  
  <p>Does not get called on the SCNNode object.</p>
  
  <p><strong>To set the scene</strong></p>
  
  <p>I am using gravity to pull down an object. When an object goes too far down, it automatically disappears and the draw calls and polygon counts decrease. So the SCNNode is definitely being destroyed, but is there a way I could hook into the destruction?</p>