ios – 使用SKEffectNode逐步模糊SKShapeNode

我正试图在我的程序中模糊SKShapenode.但是,我希望shapenode逐渐模糊,持续时间约为1秒.我如何实现这一目标？目前的代码立即模糊了它.

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)           
}

filter.SETVALue(10,forKey: "inpuTradius")