使用CAEmitterLayer创建爆炸效果

CAEmitterLayer是一个高性能的粒子引擎，被用来创建实时例子动画如：烟雾，火，雨等等这些效果。使用如下：

   let emitter = CAEmitterLayer()
    emitter.frame = self.view.bounds
    self.view.layer.addSublayer(emitter)
    
    emitter.renderMode = kCAEmitterLayerAdditive
    emitter.emitterPosition = CGPointMake(emitter.frame.size.width / 2.0, emitter.frame.size.height / 2.0)
    
    let cell = CAEmitterCell()
    cell.contents = UIImage.init(named: "spark")?.CGImage
    cell.birthRate = 150
    cell.lifetime = 5.0
    cell.color = UIColor.init(colorLiteralRed: 1, green: 0.5, blue: 0.1, alpha: 1.0).CGColor
    cell.alphaSpeed = -0.4
    cell.velocity = 50
    cell.velocityRange = 50
    cell.emissionRange = CGFloat(M_PI*2.0)
    
    emitter.emitterCells = [cell]

效果如下：

spark.png资源：