每当我尝试调用它时,以下代码都会在我的GameScene类的行pickUp.spawnShield()
上产生错误。
编译器没有关于导致错误的原因的消息,但我认为这可能与我的var pickUp: Pickup!
为零的事实有关。如果是这种情况,我该如何正确地初始化它?
class Pickup {
var game: GameScene!
func spawnShield() {
let randomXStart = Random().random(min: game.gameArea.minX + game.player.size.width/2, max: game.gameArea.maxX - game.player.size.width/2)
let randomXEnd = Random().random(min: game.gameArea.minX + game.player.size.width/2, max: game.gameArea.maxX - game.player.size.width/2)
let startPoint = CGPoint(x: randomXStart, y: game.size.height * 1.1)
let endPoint = CGPoint(x: randomXEnd, y: -game.size.height * 0.1)
let shield = SKSpriteNode(imageNamed: "shieldDrop")
shield.setScale(2)
shield.position = startPoint
shield.zPosition = 3
game.addChild(shield)
let moveShield = SKAction.move(to: endPoint, duration: TimeInterval(Helper().randomBetweenTwoNumbers(firstNumber: 3, secondNumber: 5)))
shield.run(moveShield)
}
}
然后我在课堂上这样称呼它:
class GameScene: SKScene, SKPhysicsContactDelegate {
var pickUp: Pickup!
override init(size: CGSize) {
....
pickUp = Pickup() //something like this?
super.init(size: size)
}
func startNewLevel() {
pickUp.spawnShield()
}
}
答案 0 :(得分:2)
首先:你必须在var pickUp中创建一个存储(引用)的Pickup类实例。我没有看到像
这样的东西class Pickup {
weak var game: GameScene?
init(game: GameScene) {
self.game = game
}
func spawnShield() {...}
}
class GameScene: SKScene, SKPhysicsContactDelegate {
var pickUp: Pickup!
override init(size: CGSize) {
super.init(size: size)
pickUp = Pickup(game: self)
}
第二:我没有太多理由让pickUp隐式解包(!)。我宁愿提出弱var pickUp:Pickup?以避免引用周期(如果在周期中引用)
第三:奇怪的是你没有看到缺少初始化程序的编译错误,因为你的类中有属性,然后必须定义初始化程序。初始化类属性后,不要忘记在初始化程序中调用 super.init(...)。
答案 1 :(得分:0)
在这里,我想你可以做这样的事情
class GameScene: SKScene, SKPhysicsContactDelegate {
var pickUp = Pikup()
func startNewLevel() {
pickUp.spawnShield()
}
}
或者你可以在调用spawnShield()之前初始化变量“pikUp”,也许在你编写的init方法中。
所以也要确保在初始化之后使用'game'变量,因为正如我在你的代码中看到的那样,它也会崩溃,因为当你使用它时它是零。