title: Blurring a SKShapeNode incrementally using SKEffectNode
body: <p>I'm trying to blur a SKShapenode in my program. However, I want the shapenode to blur progressively, with a duration of about 1 second. How do I achieve that? The current code blurs it instantly.</p>
  
  <pre><code>func generateAnimation() {
  
  var blurAction : SKAction = SKAction.runBlock{
     //the method below returns a shapeNode
      var circle = self.generateImage()
      var effect : SKEffectNode = SKEffectNode()
      var filter : CIFilter = CIFilter(name:"CIGaussianBlur")
      filter.setValue(10, forKey: "inputRadius")
      effect.filter = filter
      effect.addChild(circle)
      self.addChild(effect)           
  }
  </code></pre>