title: SceneKit: How to detect contact without collision iOS
body: <p>I'm making a Space Shooter game on Scene Kit and I want the asteroids to explode when the ship gets contact with them, I don't want them to collide, I just want to know when they contact each other. </p>
  
  <p>The problem is that I don't know how to implement a collision detection when the ship intersects the asteroid. Like for example, I want Xcode to log "COLLIDED" when they actually get contact with each other.</p>
  
  <p>I already added the <code>categoryBitMask</code> and the <code>collisionBitMask</code> for both objects. So, how could I achieve this? By the way, I'm doing everything on Swift.</p>