如何将SKnode子类化以创建具有多个独立“车道”的场景？

import SpriteKit

class Lane: SKNode {
    // 添加车道元素的方法
    func addElement(element: SKNode) {
        addChild(element)
    }
}

let lane1 = Lane()
lane1.position = CGPoint(x: 0, y: 0)
lane1.size = CGSize(width: scene.size.width, height: 100)

let lane2 = Lane()
lane2.position = CGPoint(x: 0, y: -100)
lane2.size = CGSize(width: scene.size.width, height: 100)

scene.addChild(lane1)
scene.addChild(lane2)

let car1 = SKSpriteNode(imageNamed: "car1")
lane1.addElement(element: car1)

let car2 = SKSpriteNode(imageNamed: "car2")
lane2.addElement(element: car2)