新年开工啦，放个小烟花庆祝一下

func generateNewSpriteNode(color: UIColor) -> SKSpriteNode{
        let node = SKSpriteNode(color: color, size: CGSize(width: 30, height: 30))
        node.position = CGPoint(x: 0, y: -500)
        node.physicsBody = SKPhysicsBody(circleOfRadius: 30)
        node.physicsBody?.isDynamic = true
        node.physicsBody?.restitution = 0
        
        let fire = SKEmitterNode(fileNamed: "Fire")
        fire?.targetNode = self
        fire?.particleColorBlendFactor = 1.0
        fire?.particleColorSequence = nil
        fire?.particleColor = color
        node.addChild(fire!)
        
        self.addChild(node)
        
        return node
    }

func fire(){
        // create particle
        let random = Int(arc4random_uniform(UInt32(self.colors.count)))
        let node: SKSpriteNode = generateNewSpriteNode(color: colors[random])
        let randomAngle = Int.random(in: -100...100)
        node.physicsBody?.applyImpulse(CGVector(dx: randomAngle, dy: 300))
    }

 // 定时器
        Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { time in
            self.fire()
        }