title: Add glowing effect to an SKSpriteNode
body: <p>I have a moving black image on a dark screen, to make it easier to see I would like to add in a white glow to the image. This is my code for the moving image:</p>
  
  <pre><code>   Ghost = SKSpriteNode(imageNamed: "Ghost1")
  Ghost.size = CGSize(width: 50, height: 50)
  Ghost.position = CGPoint(x: self.frame.width / 2 - Ghost.frame.width, y: self.frame.height / 2)
  
  Ghost.physicsBody = SKPhysicsBody(circleOfRadius: Ghost.frame.height / 1.4)
  Ghost.physicsBody?.categoryBitMask = PhysicsCatagory.Ghost
  Ghost.physicsBody?.collisionBitMask = PhysicsCatagory.Ground | PhysicsCatagory.Wall
  Ghost.physicsBody?.contactTestBitMask = PhysicsCatagory.Ground | PhysicsCatagory.Wall | PhysicsCatagory.Score
  Ghost.physicsBody?.affectedByGravity = false
  Ghost.physicsBody?.isDynamic = true
  Ghost.zPosition = 2
  
  self.addChild(Ghost)
  </code></pre>
  
  <p>I'm not sure how or what to use to add in a glow, if you need more information please ask.</p>