ios - 在 Swift 中检测到碰撞时更改图像

Question

我需要在玩家碰撞时更改敌人 SKSpriteNode 的图像，但在游戏中我会有很多敌人，我只想更改选定的一个。

Enemy.name 是生命的数量，我不知道我是否可以做不同的事情。

func setupPlayer(){
    player = SKSpriteNode(imageNamed: "ball")
    player.anchorPoint = CGPoint(x: 0.5, y: 0.5)
    player.position = CGPoint(x: size.width/2, y: 60)
    player.zPosition = Layer.Player.rawValue
    player.physicsBody = SKPhysicsBody(circleOfRadius: player.size.width / 2)
    player.physicsBody?.mass = 1
    player.physicsBody?.restitution = 0.7
    player.physicsBody?.dynamic = true
    player.physicsBody?.categoryBitMask = playerCategory
    player.physicsBody?.contactTestBitMask = enemyCategory 
    worlNode.addChild(player)
    nuevoPlayerControl = true
}

func setupEnemy(){
    if nuevoPlayerControl == true && nuevoPlayer == true{
        enemy = SKSpriteNode(imageNamed: "ball")
        enemy.anchorPoint = CGPoint(x: 0.5, y: 0.5)
        enemy.zPosition = Layer.Player.rawValue
        enemy.position = CGPoint(x: 250, y: 300)
        enemy.physicsBody?.mass = 1
        enemy.zRotation = player.zRotation
        enemy.size = player.size
        enemy.physicsBody = SKPhysicsBody(circleOfRadius: enemy.size.width/2)
        enemy.physicsBody?.friction = 1
        enemy.physicsBody?.dynamic = true
        enemy.physicsBody?.categoryBitMask = enemyCategory
        enemy.physicsBody?.contactTestBitMask = playerCategory 
        enemy.name = "3"
        worlNode.addChild(enemy)
    }
}

func didBeginContact(contact: SKPhysicsContact) {
    var body1 : SKPhysicsBody!
    var body2 : SKPhysicsBody!

    if contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask {
        body1 = contact.bodyA
        body2 = contact.bodyB
    }
    else  {
        body1 = contact.bodyB
        body2 = contact.bodyA
    }
    if body1.categoryBitMask == playerCategory && body2.categoryBitMask == enemyCategory {
        //here the enemy lose a live and the image should change
        let lives = body2.node?.name
        if lives! == "3" {
            body2.node?.name = "2"
        }
        if lives! == "2" {
            body2.node?.name = "1"
        }
        if lives! == "1" {
            body2.node?.removeFromParent()
        }
        print(lives)
    }
 }

Answer 1

如果您需要，您可以随时为敌人编写一个自定义类，它继承自 SKSpriteNode，您可以在其中拥有一个名为 numLives 的属性，因此您可以为此目的使用名称字符串并获取生命数通过enemy.numLives。最简单的方法可能是使用 name 字符串的第一部分作为生命数，第二部分作为你的敌人识别，当你需要生命数或名字时，你只需解析它得到你想要的。例如:

//when you create an enemy:
enemy.name = "3 bigEnemy"

然后，如果你需要访问它，要么使用 for-in 解析/循环，要么使用 subStringWithRange 获取你需要的字符串的一部分:

//to get the number of lives:
let lives = enemy.name.substringWithRange(NSRangeMake(0, 1))
//to get the name of the enemy:
let name = enemy.name.substringWithRange(NSRangeMake(3, enemy.name.length))

碰撞时更改图像的方向正确。您剩下要做的就是更改 body.node 的纹理。如果您有一个图像，您只需使用:

var textureToChangeTo: SKTexture = SKTexture.textureWithImage("yourImageNameHere")
body.node?.texture = textureToChangeTo