问如何在SpriteKit中制作移动障碍物

EN

    func createClouds() -> [SKSpriteNode]{


    var clouds = [SKSpriteNode]();

    for _ in 0 ..< 2 {

        let cloud1 = SKSpriteNode(imageNamed: "Cloud 1")
        cloud1.name = "1"
        let cloud2 = SKSpriteNode(imageNamed: "Cloud 2")
        cloud2.name = "2"
        let cloud3 = SKSpriteNode(imageNamed: "Cloud 3")
        cloud3.name = "3"
        let darkCloud = SKSpriteNode(imageNamed: "Dark Cloud")
        darkCloud.name = "Dark Cloud"




        cloud1.xScale = 0.9
        cloud1.yScale = 0.9

        cloud2.xScale = 0.9
        cloud2.yScale = 0.9

        cloud3.xScale = 0.9
        cloud3.yScale = 0.9

        darkCloud.xScale = 0.9
        darkCloud.yScale = 0.9

        cloud1.physicsBody = SKPhysicsBody(rectangleOf: CGSize(width: cloud1.size.width - 5, height: cloud1.size.height - 6));
        cloud1.physicsBody?.affectedByGravity = false;
        cloud1.physicsBody?.restitution = 0;
        cloud1.physicsBody?.categoryBitMask = ColliderType.Cloud;
        cloud1.physicsBody?.collisionBitMask = ColliderType.Player;

        cloud2.physicsBody = SKPhysicsBody(rectangleOf: CGSize(width: cloud2.size.width - 5, height: cloud2.size.height - 6));
        cloud2.physicsBody?.affectedByGravity = false;
        cloud2.physicsBody?.restitution = 0;
        cloud2.physicsBody?.categoryBitMask = ColliderType.Cloud;
        cloud2.physicsBody?.collisionBitMask = ColliderType.Player;


        cloud3.physicsBody = SKPhysicsBody(rectangleOf: CGSize(width: cloud3.size.width - 5, height: cloud3.size.height - 6));
        cloud3.physicsBody?.affectedByGravity = false;
        cloud3.physicsBody?.restitution = 0;
        cloud3.physicsBody?.categoryBitMask = ColliderType.Cloud;
        cloud3.physicsBody?.collisionBitMask = ColliderType.Player;

        darkCloud.physicsBody = SKPhysicsBody(rectangleOf: darkCloud.size)
        darkCloud.physicsBody?.affectedByGravity = false;
        darkCloud.physicsBody?.categoryBitMask = ColliderType.DarkCloudAndCollectables;
        darkCloud.physicsBody?.collisionBitMask = ColliderType.Player;

        clouds.append(cloud1)
        clouds.append(cloud2)
        clouds.append(cloud3)
        clouds.append(darkCloud)

    }

    clouds = shuffle(cloudsArray: clouds);

    return clouds


}

func arrangeCloudsInScene(scene: SKScene, distanceBetweenClouds: CGFloat, center: CGFloat, minX: CGFloat, maxX: CGFloat, player: Player, initialClouds: Bool) {

    var clouds = createClouds()

    if initialClouds{

        while(clouds[0].name == "Dark Cloud") {
            clouds = shuffle(cloudsArray: clouds);

        }
    }


    var positionY = CGFloat();

    if initialClouds {
        positionY = center - 100;
    } else {
        positionY = lastCloudPositionY;
    }

    var random = 0;

    for i in 0...clouds.count - 1 {

        var randomX = CGFloat();

        if random == 0 {
            randomX = randomBetweenNumbers(firstNum: center + 90, secondNum: maxX);
            random = 1;
        } else if random == 1{
            randomX = randomBetweenNumbers(firstNum: center - 90, secondNum: minX)
            random = 0;
        }

        clouds[i].position = CGPoint(x: randomX, y: positionY);
        clouds[i].zPosition = 3;

        if !initialClouds {

            if Int(randomBetweenNumbers(firstNum: 0, secondNum: 7)) >= 3 {

                if clouds[i].name != "Dark Cloud" {
                    let collectable = collectableController.getCollectable();
                    collectable.position = CGPoint(x: clouds[i].position.x, y: clouds[i].position.y + 60);

                    scene.addChild(collectable);

                }

            }

        }