title: Swift SKCropNode can someone explain this behavior?
body: <p>I have a grid of 16 SKCropNode objects. Each contains a SKShapeNode used as a mask, and a SKSpriteNoe. In this image with the mask not set you can see all 16 object appear in a grid. </p>
  
  <p><a href="https://github.com/soggybag/Grid" rel="nofollow noreferrer">https://github.com/soggybag/Grid</a></p>
  
  <p><a href="https://i.stack.imgur.com/oTxKd.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/oTxKd.jpg" alt="Without mask all items appear"></a></p>
  
  <p><a href="https://i.stack.imgur.com/JytLG.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/JytLG.jpg" alt="When the mask is set some of the items disappear? Seems there is a pattern here: 1, 4, 6, 9, 11, and 14. My guess is 17 would be gone."></a></p>
  
  <p>Interaction is strange also. Tapping makes the image sprite move down and disappear moving out of the mask. You can tap the area below the orange, where a sprite would be hidden, and it recognizes the tap event. </p>
  
  <p>Even stranger you not tap the sprite in the upper right? </p>