Swift致命错误(启动时崩溃)

Question

我得到错误

fatal error: unexpectedly found nil while unwrapping an Optional value

只有当我把这条线放在中时才会发生这种情况

    override func update(currentTime: CFTimeInterval) {
    /* Called before each frame is rendered */
    if wall.position.x == 0 {
        score = score + 1
        scoreLabel.text = "(score)"
    }

}
}

错误显示的行是"if wall.position.x==0｛"我指的是它显示线程错误的位置"EXC_BAD_INSTRUCTION（代码=EXC_I386_INVOP，子代码=0x0）"

全代码

import SpriteKit
class GameScene: SKScene, SKPhysicsContactDelegate {

var movingGround: CSMovingGround!
var hero: CSHero!
var cloudGenerator: CSCloudGenerator!
var wallGenerator: CSWallGenerator!
var wall: CSWall!
var scoreLabel = SKLabelNode()
var score: Int = 0
var isStarted = false
var heroCategory: UInt32 = 1<<1
var wallCategory: UInt32 = 1<<2
var groundCategory: UInt32 = 1<<2


override func didMoveToView(view: SKView) {
    backgroundColor = UIColor(red: 159.0/255.0, green: 201.0/255, blue: 244.0/255.0, alpha: 1.0)
    /*
    let backgroundTexture = SKTexture(imageNamed: "background.png")
    let backgroundImage = SKSpriteNode(texture: backgroundTexture, size: view.frame.size)
    backgroundImage.position = view.center
    addChild(backgroundImage)
    */

    // add ground
    movingGround = CSMovingGround(size: CGSizeMake(view.frame.width, kCSGroundHeight))
    movingGround.position = CGPointMake(0, view.frame.size.height/2)
    self.addChild(movingGround)
    // add hero
    hero = CSHero()
    hero.position = CGPointMake(70, movingGround.position.y + movingGround.frame.size.height/2 + hero.frame.size.height/2)
    hero.physicsBody = SKPhysicsBody(rectangleOfSize: hero.size)
    hero.physicsBody?.dynamic = true
    hero.physicsBody?.allowsRotation = false
    hero.physicsBody!.collisionBitMask = heroCategory | wallCategory
    hero.physicsBody!.contactTestBitMask = wallCategory | heroCategory | groundCategory
    self.addChild(hero)
    hero.breathe()

    // add cloud generator
    cloudGenerator = CSCloudGenerator(color: UIColor.clearColor(), size: view.frame.size)
    cloudGenerator.position = view.center
    addChild(cloudGenerator)
    cloudGenerator.populate(7)
    cloudGenerator.startGeneratingWithSpawnTime(5)
    // add wall generator
    wallGenerator = CSWallGenerator(color: UIColor.clearColor(), size: view.frame.size)
    wallGenerator.position = view.center
    wallGenerator.physicsBody = SKPhysicsBody(edgeLoopFromRect : wallGenerator.frame)
    wallGenerator.physicsBody?.dynamic = false
    wallGenerator.physicsBody!.collisionBitMask = wallCategory | heroCategory
    self.addChild(wallGenerator)

    let ground1 = SKSpriteNode(color: UIColor.clearColor(), size: CGSizeMake(view.frame.size.width, 20))
    ground1.position = view.center
    ground1.physicsBody = SKPhysicsBody(rectangleOfSize: ground1.size)
    ground1.physicsBody!.dynamic = false
    ground1.physicsBody!.affectedByGravity = false
    ground1.physicsBody!.categoryBitMask = groundCategory
    ground1.physicsBody!.collisionBitMask = groundCategory | heroCategory
    self.addChild(ground1)
    let ground2 = SKSpriteNode(color: UIColor.blackColor(), size: CGSizeMake(view.frame.size.width, 20))
    ground2.position = CGPointMake(284, 98)
    ground2.physicsBody = SKPhysicsBody(rectangleOfSize: ground2.size)
    ground2.physicsBody!.dynamic = false
    ground2.physicsBody!.affectedByGravity = false
    ground2.physicsBody!.categoryBitMask = groundCategory
    ground2.physicsBody!.collisionBitMask = groundCategory | heroCategory
    self.addChild(ground2)

    physicsWorld.contactDelegate = self
    scoreLabel.fontName = "score"
    scoreLabel.fontColor = UIColor.blackColor()
    scoreLabel.fontSize = 40
    scoreLabel.text = "0"
    scoreLabel.position = CGPoint(x: 50, y: 275)
    self.addChild(scoreLabel)

}

func start() {
    isStarted = true
    hero.stop()
    hero.startRunning()
    movingGround.start()
    wallGenerator.startGeneratingWallsEvery(1)
}

override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
    if !isStarted {
        start()
    } else {
        hero.flip()
    }

}

func didBeginContact(contact: SKPhysicsContact) {
    var firstBody = SKPhysicsBody()
    var secondBody = SKPhysicsBody()
    if contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask {
        firstBody = contact.bodyA
        secondBody = contact.bodyB
    } else {
        firstBody = contact.bodyB
        secondBody = contact.bodyA
    }
    if (firstBody.categoryBitMask & UInt32(heroCategory)) != 0 && (secondBody.categoryBitMask & UInt32(wallCategory)) != 0 {
        wallGenerator.removeFromParent()
        let reveal = SKTransition.flipHorizontalWithDuration(0.5)
        let scene = GameOverScene(size: self.size, won: false)
        self.view?.presentScene(scene, transition: reveal)
    }
}

override func update(currentTime: CFTimeInterval) {
    /* Called before each frame is rendered */
    if wall.position.x < 70 {
        score++
        scoreLabel.text = "(score)"
    }

}
}

import Foundation

导入SpriteKit

类CSWall:SKSpriteNode｛

let WALL_WIDTH: CGFloat = 30.0
let WALL_HEIGHT: CGFloat = 50.0
let WALL_COLOR = UIColor.blackColor()
override init() {
    super.init(texture: nil, color: WALL_COLOR, size: CGSizeMake(WALL_WIDTH, WALL_HEIGHT))
    startMoving()
}
required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}
func startMoving() {
    let moveLeft = SKAction.moveByX(-300, y: 0, duration: 1)
    runAction(SKAction.repeatActionForever(moveLeft))
}

}

Answer 1

因此，错误似乎非常确信您正在尝试访问零值的属性。wall.position.x可能未初始化。如果你的值不存在，你可以检查nil，什么也不做，但你可能需要首先弄清楚为什么它没有初始化，因为它看起来很重要。

if let wallPosition = wall.position.x {
     if (wallPosition == 0){
         score ++
         scoreLabel.text = "(score)"
     }
}