如何根据颜色检测碰撞？

Question

我试图检测正方形的4个边缘处的碰撞，每个边缘是不同的颜色。截图：

目标是获得它，以便如果某个颜色的SKSpriteNode（圆圈）触及相同的颜色边缘，则将其从场景中移除。每个圆圈在屏幕的每个边缘随机产生。

我尝试在每个边缘添加4个SKSprite节点，并使用didBeginContact func检测碰撞。我还尝试通过gameScene.sks文件执行此操作，但由于某种原因，即使添加了它未检测到的collisionBitMask类别，它也无法检测到冲突。但是我仍然无法让它发挥作用而且非常令人沮丧，请帮助。

import SpriteKit

class GameScene: SKScene, SKPhysicsContactDelegate {

    var bombColor = SKSpriteNode()

    var blueBombCatagory : UInt32 = 0x1 << 0
    var redBombCatagory : UInt32 = 0x1 << 2
    var yellowBombCatagory : UInt32 = 0x1 << 3
    var greenBombCatagory : UInt32 = 0x1 << 4

    var blueSideContact : UInt32 = 0x1 << 5
    var yellowSideContact : UInt32 = 0x1 << 6
    var greenSideContact : UInt32 = 0x1 << 7
    var redSideContact : UInt32 = 0x1 << 8

    var speedFactor:CGFloat = 0.5
    var spawnInterval =  0.4 + (NSTimeInterval(arc4random_uniform(5)) * 0.25)
    var spawnTimer = NSTimer()

    override func didMoveToView(view: SKView) {
        /* Setup your scene here */

        self.physicsWorld.contactDelegate = self
        self.physicsWorld.gravity = CGVectorMake(0, 0)

        var rotationPoint = childNodeWithName("rotationPoint")
        var player = childNodeWithName("player")

        var blueSide = childNodeWithName("blueSidePhyscis") as! SKSpriteNode!
        let redSide = childNodeWithName("redSide") as! SKSpriteNode!
        let greenSide = childNodeWithName("greenSide") as! SKSpriteNode!
        let yellowSide = childNodeWithName("yellowSide") as! SKSpriteNode!

        blueSide?.physicsBody!.categoryBitMask = blueSideContact
        blueSide?.physicsBody!.contactTestBitMask = blueBombCatagory
        redSide?.physicsBody!.categoryBitMask = redSideContact
        redSide?.physicsBody!.contactTestBitMask = redBombCatagory
        greenSide?.physicsBody!.categoryBitMask = greenSideContact
        greenSide?.physicsBody!.contactTestBitMask = greenBombCatagory
        yellowSide?.physicsBody!.categoryBitMask = yellowSideContact
        yellowSide?.physicsBody!.contactTestBitMask = yellowBombCatagory

        spawnTimer = NSTimer.scheduledTimerWithTimeInterval(2, target: self, selector: Selector("spawnPoint"), userInfo: nil, repeats: true)
    }

    func didBeginContact(contact: SKPhysicsContact) {
        //this gets called automatically when two objects begin contact with each other
        if (contact.bodyA.categoryBitMask == blueSideContact && contact.bodyB.categoryBitMask == blueBombCatagory)  {
            println("blue")
            deletion()

        } else if(contact.bodyB.categoryBitMask == blueSideContact && contact.bodyA.categoryBitMask == blueBombCatagory) {
            println("blue")
            deletion()

        }else if(contact.bodyA.categoryBitMask == redSideContact && contact.bodyB.categoryBitMask == redBombCatagory) {
            println("red")
            deletion()

        } else if(contact.bodyA.categoryBitMask == greenSideContact && contact.bodyB.categoryBitMask == greenBombCatagory) {
            println("green")
            deletion()

        } else if(contact.bodyA.categoryBitMask == yellowSideContact && contact.bodyB.categoryBitMask == yellowBombCatagory) {
            println("yellow")
            deletion()
        }
    }


    override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
        /* Called when a touch begins */

        for touch in (touches as! Set<UITouch>) {

            let location = touch.locationInNode(self)

            if location.x < self.size.width/2 {
                println("Left")
                rotateLeft()
            }
            else {
                println("Right")
                rotateRight()
            }

        }

    }

    override func update(currentTime: CFTimeInterval) {
        /* Called before each frame is rendered */
    }

    func deletion() {
        bombColor.removeFromParent()
    }

    func rotateLeft() {

        var rotationPoint : SKNode = childNodeWithName("rotationPoint")!

        let rotationLeft = SKAction.rotateByAngle(CGFloat(1.570793268), duration: 0.3)
        rotationPoint.runAction(rotationLeft)

        //player.runAction(rotationLeft)

    }

    func spawnPoint() {

        let spritePicker = arc4random() % 4
        var rotationPoint : SKNode = childNodeWithName("rotationPoint")!

        switch spritePicker{

        case 0:
            bombColor = SKSpriteNode(imageNamed: "BombBlue")
            bombColor.size = CGSize(width: 20, height: 20)
            bombColor.physicsBody = SKPhysicsBody(circleOfRadius: 10)
            bombColor.physicsBody?.categoryBitMask = 4294967294
            bombColor.physicsBody?.usesPreciseCollisionDetection = true
            bombColor.physicsBody?.dynamic = true
            bombColor.physicsBody?.collisionBitMask = 4294967295
            break;
        case 1:
            bombColor = SKSpriteNode(imageNamed: "BombRed")
            bombColor.size = CGSize(width: 20, height: 20)
            bombColor.physicsBody = SKPhysicsBody(circleOfRadius: 10)
            bombColor.physicsBody?.categoryBitMask = redBombCatagory
            bombColor.physicsBody?.usesPreciseCollisionDetection = true
            bombColor.physicsBody?.dynamic = true
            bombColor.physicsBody?.collisionBitMask = redSideContact
            break;
        case 2:
            bombColor = SKSpriteNode(imageNamed: "BombYellow")
            bombColor.size = CGSize(width: 20, height: 20)
            bombColor.physicsBody = SKPhysicsBody(circleOfRadius: 10)
            bombColor.physicsBody?.categoryBitMask = yellowBombCatagory
            bombColor.physicsBody?.usesPreciseCollisionDetection = true
            bombColor.physicsBody?.dynamic = true
            bombColor.physicsBody?.collisionBitMask = yellowSideContact
            break;
        case 3:
            bombColor = SKSpriteNode(imageNamed: "BombGreen")
            bombColor.size = CGSize(width: 20, height: 20)
            bombColor.physicsBody = SKPhysicsBody(circleOfRadius: 10)
            bombColor.physicsBody?.categoryBitMask = greenBombCatagory
            bombColor.physicsBody?.usesPreciseCollisionDetection = true
            bombColor.physicsBody?.dynamic = true
            bombColor.physicsBody?.collisionBitMask = greenSideContact
            break;
        default:
            break;
        }

        let RandomNumber = arc4random() % 1

        switch RandomNumber{

        case 0:

            bombColor.position.x = CGRectGetMidX(self.frame)

            bombColor.position.y = CGRectGetMaxY(self.frame)

            self.addChild(bombColor)

            break;

        case 1:

            bombColor.position.x = CGRectGetMidX(self.frame)

            bombColor.position.y = CGRectGetMinY(self.frame)

            self.addChild(bombColor)

            break;

        case 2:

            bombColor.position.x = CGRectGetMinX(self.frame)

            bombColor.position.y = CGRectGetMidY(self.frame)

            self.addChild(bombColor)

            break;

        case 3:

            bombColor.position.x = CGRectGetMaxX(self.frame)

            bombColor.position.y = CGRectGetMidY(self.frame)

            self.addChild(bombColor)

            break;

        default:
            break;
        }

        let speed = 2 - speedFactor
        bombColor.runAction(SKAction.moveTo(rotationPoint.position, duration: NSTimeInterval(2)))

    }

    func rotateRight() {

        var rotationPoint : SKNode = childNodeWithName("rotationPoint")!

        let rotationRight = SKAction.rotateByAngle(CGFloat(-1.570793268), duration: 0.3)

        rotationPoint.runAction(rotationRight)
        //player.runAction(rotationRight)

    }
}