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我在一个Swift Playground上有一个乒乓球游戏，我通过在线教程做了一个教程，但是我的助理编辑不会显示任何东西！我的乒乓球比赛在哪里！？我的代码在图片下面，显示没有任何东西显示出来。为什么我的Swift Playground中不会出现任何东西？
import SpriteKit
import PlaygroundSupport
// Declare some global constants
let width = 800 as CGFloat
let height = 1200 as CGFloat
let racketHeight = 150 as CGFloat
let ballRadius = 20 as CGFloat
// Three types of collision objects possible
enum CollisionTypes: UInt32 {
case Ball = 1
case Wall = 2
case Racket = 4
}
// Racket direction
enum Direction: Int {
case None = 0
case Up = 1
case Down = 2
}
// Make a SpriteKit scene
class gameScene: SKScene, SKPhysicsContactDelegate {
let racketSpeed = 500.0
var direction = Direction.None
var score = 0
var gameRunning = false
// Screen elements
var racket: SKShapeNode?
var ball: SKShapeNode?
let scoreLabel = SKLabelNode()
// Initialize objects during first start
override func sceneDidLoad() {
super.sceneDidLoad()
scoreLabel.fontSize = 40
scoreLabel.position = CGPoint(x: width/2, y: height - 100)
self.addChild(scoreLabel)
createWalls()
createBall(position: CGPoint(x: width/2, y: height/2))
createRacket()
startNewGame()
self.physicsWorld.contactDelegate = self
}
// Create the ball sprite
func createBall(position: CGPoint) {
let physicsBody = SKPhysicsBody(circleOfRadius: ballRadius)
ball = SKShapeNode(circleOfRadius: ballRadius)
physicsBody.categoryBitMask = CollisionTypes.Ball.rawValue
physicsBody.collisionBitMask = CollisionTypes.Wall.rawValue | CollisionTypes.Ball.rawValue | CollisionTypes.Racket.rawValue
physicsBody.affectedByGravity = false
physicsBody.restitution = 1
physicsBody.linearDamping = 0
physicsBody.velocity = CGVector(dx: -500, dy: 500)
ball!.physicsBody = physicsBody
ball!.position = position
ball!.fillColor = SKColor.white
}
// Create the walls
func createWalls() {
createWall(rect: CGRect(origin: CGPoint(x: 0, y: 0), size: CGSize(width: ballRadius, height: height)))
createWall(rect: CGRect(origin: CGPoint(x: 0, y: 0), size: CGSize(width: width, height: ballRadius)))
createWall(rect: CGRect(origin: CGPoint(x: 0, y: height - ballRadius), size: CGSize(width: width, height: ballRadius)))
}
func createWall(rect: CGRect) {
let node = SKShapeNode(rect: rect)
node.fillColor = SKColor.white
node.physicsBody = getWallPhysicsbody(rect: rect)
self.addChild(node)
}
// Create the physics objetcs to handle wall collisions
func getWallPhysicsbody(rect: CGRect) -> SKPhysicsBody {
let physicsBody = SKPhysicsBody(rectangleOf: rect.size, center: CGPoint(x: rect.midX, y: rect.midY))
physicsBody.affectedByGravity = false
physicsBody.isDynamic = false
physicsBody.collisionBitMask = CollisionTypes.Ball.rawValue
physicsBody.categoryBitMask = CollisionTypes.Wall.rawValue
return physicsBody
}
// Create the racket sprite
func createRacket() {
racket = SKShapeNode(rect: CGRect(origin: CGPoint.zero, size: CGSize(width: ballRadius, height: racketHeight)))
self.addChild(racket!)
racket!.fillColor = SKColor.white
let physicsBody = SKPhysicsBody(rectangleOf: racket!.frame.size, center: CGPoint(x: racket!.frame.midX, y: racket!.frame.midY))
physicsBody.affectedByGravity = false
physicsBody.isDynamic = false
physicsBody.collisionBitMask = CollisionTypes.Ball.rawValue
physicsBody.categoryBitMask = CollisionTypes.Racket.rawValue
physicsBody.contactTestBitMask = CollisionTypes.Ball.rawValue
racket!.physicsBody = physicsBody
}
// Start a new game
func startNewGame() {
score = 0
scoreLabel.text = "0"
racket!.position = CGPoint(x: width - ballRadius * 2, y: height/2)
let startLabel = SKLabelNode(text: "Game Over")
startLabel.position = CGPoint(x: width/2, y: height/2)
startLabel.fontSize = 160
self.addChild(startLabel)
// Animated countdown
let fadeIn = SKAction.fadeIn(withDuration: 0.5)
let fadeOut = SKAction.fadeOut(withDuration: 0.5)
startLabel.text = "3"
startLabel.run(SKAction.sequence([fadeIn, fadeOut]), completion: {
startLabel.text = "2"
startLabel.run(SKAction.sequence([fadeIn, fadeOut]), completion: {
startLabel.text = "1"
startLabel.run(SKAction.sequence([fadeIn, fadeOut]), completion: {
startLabel.text = "0"
startLabel.run(SKAction.sequence([fadeIn, fadeOut]), completion: {
startLabel.removeFromParent()
self.gameRunning = true
self.ball!.position = CGPoint(x: 30, y: height/2)
self.addChild(self.ball!)
})
})
})
})
}
// Handle touch events to move the racket
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches {
let location = touch.location(in: self)
if location.y > height/2 {
direction = Direction.Up
} else if location.y < height/2{
direction = Direction.Down
}
}
}
// Stop racket movement
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
direction = Direction.None
}
// Game loop:
var dt = TimeInterval(0)
override func update(_ currentTime: TimeInterval) {
if gameRunning {
super.update(currentTime)
checkGameOver()
if dt > 0 {
moveRacket(dt: currentTime - dt)
}
dt = currentTime
}
}
// Move the racket up or down
func moveRacket(dt: TimeInterval) {
if direction == Direction.Up && racket!.position.y < height - racketHeight {
racket!.position.y = racket!.position.y + CGFloat(racketSpeed * dt)
} else if direction == Direction.Down && racket!.position.y > 0 {
racket!.position.y = racket!.position.y - CGFloat(racketSpeed * dt)
}
}
// Check if the ball is still on screen
// Game Over animation
func checkGameOver() {
if ball!.position.x > CGFloat(width) {
gameRunning = false
ball!.removeFromParent()
let gameOverLabel = SKLabelNode(text: "Game Over")
gameOverLabel.position = CGPoint(x: width/2, y: height/2)
gameOverLabel.fontSize = 80
self.addChild(gameOverLabel)
// Game Over animation
let rotateAction = SKAction.rotate(byAngle: CGFloat(M_PI), duration: 1)
let fadeInAction = SKAction.fadeIn(withDuration: 2)
gameOverLabel.run(SKAction.repeat(rotateAction, count: 2))
gameOverLabel.run(SKAction.scale(to: 0, duration: 2.5), completion: {
gameOverLabel.removeFromParent()
self.startNewGame()
})
}
}
// Detect collisions between ball and racket to increase the score
func didBegin(_ contact: SKPhysicsContact) {
if contact.bodyA.categoryBitMask == CollisionTypes.Racket.rawValue || contact.bodyB.categoryBitMask == CollisionTypes.Racket.rawValue {
score += 1
scoreLabel.text = String(score)
}
}
}
//Initialize the playground and start the scene:
let skView = SKView(frame: CGRect(origin: CGPoint.zero, size: CGSize(width: width, height: height)))
let scene = gameScene(size: skView.frame.size)
skView.presentScene(scene)
PlaygroundPage.current.liveView = skView