平台从左向右移动然后反之亦然的最佳方法是什么？

Question

使用Swift SpriteKit制作像Doodle Jump这样的游戏，我希望平台从屏幕左侧不断反弹到右边。这样做的最佳方式是什么？

import SpriteKit
import GameplayKit

class GameScene: SKScene, SKPhysicsContactDelegate {

    private var player: Player?
    private var platform: Platform?

    var playerCategory:   UInt32 = 0b1
    var platformCategory: UInt32 = 0b10
    var edgeCategory:     UInt32 = 0b100

    override func didMove(to view: SKView) {
        physicsWorld.contactDelegate = self

        //player
        player = childNode(withName: "Player") as? Player!
        player?.physicsBody?.categoryBitMask = playerCategory
        player?.physicsBody?.collisionBitMask = platformCategory | edgeCategory


        //placed platform
        platform = childNode(withName: "Platform") as? Platform!
        platform?.physicsBody?.categoryBitMask = platformCategory
        platform?.physicsBody?.collisionBitMask = edgeCategory
        platform?.physicsBody?.applyImpulse(CGVector(dx: 30, dy: 0))


        //create frame boundary
        let borderBody = SKPhysicsBody(edgeLoopFrom: self.frame)
        borderBody.friction = 0
        borderBody.restitution = 0
        borderBody.categoryBitMask = edgeCategory
        self.physicsBody = borderBody
    }

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        player?.jump()
        player?.physicsBody?.collisionBitMask = edgeCategory
    }

    override func update(_ currentTime: TimeInterval) {
        changeCollisions()
        //movePlatform()
    }

    func changeCollisions() {
        if let body = player?.physicsBody {
            let dy = body.velocity.dy
            if dy > 0 {
                // Prevent collisions if the hero is jumping
                //body.collisionBitMask = 0
            }
            else {
                // Allow collisions if the hero is falling
                body.collisionBitMask = platformCategory | edgeCategory
            }
        }
    }

    func movePlatform() {
        if ( (platform?.position.x)! <= /*-(scene?.size.width)!*/ 0 ) {
            platform?.position.x += 5
        } else {
            platform?.position.x -= 5
        }
    }
}

我目前拥有的（灰色矩形是平台）：

Answer 1

您可以使用所需的动画创建一个简单的SKAction序列：

let duration = 10 // Animation duration in seconds.
let moveRight = SKAction.moveTo(x: maxX, duration: duration/2)
let moveLeft = SKAction.moveTo(x: minX, duration: duration/2)
let moves = SKAction.repeatForever(.sequence([moveRight, moveLeft])
platform!.run(moves)