ios - SpriteKit/Swift - 当两个节点已经接触时如何检查它们的接触

Question

在我的游戏中，当游戏开始时，一些节点已经接触，但我找不到如何检测这些接触。我只成功检测到节点在游戏过程中移动并使用函数 didBeginContact 进行接触时发生的接触。

有人知道如何检测这些联系人吗？

如果需要，这是我的 didBeginContact:

func didBeginContact(contact: SKPhysicsContact) {

    var firstBody: SKPhysicsBody
    var secondBody: SKPhysicsBody
    if contact.bodyA.categoryBitMask == contact.bodyB.categoryBitMask {
        firstBody = contact.bodyA
        secondBody = contact.bodyB

        contactsList.append([firstBody.node!,secondBody.node!])
    }
}

Answer 1

我刚刚尝试让两个 Sprite 从一开始就重叠，并为我检测到接触。这是代码:

import SpriteKit

struct Collider {
    static let SmallSquare     : UInt32 = 1 << 0
    static let BigSquare       : UInt32 = 1 << 1
}

class GameScene: SKScene, SKPhysicsContactDelegate {

    override func didMoveToView(view: SKView) {

        self.physicsWorld.contactDelegate = self

        let smallSquare = SKSpriteNode(color: .orangeColor(), size: CGSize(width: 50, height:50))
        smallSquare.zPosition = 2
        smallSquare.position = CGPoint(x: frame.midX, y: frame.midY)
        smallSquare.physicsBody = SKPhysicsBody(rectangleOfSize: smallSquare.size)
        smallSquare.physicsBody?.affectedByGravity = false
        smallSquare.physicsBody?.categoryBitMask = Collider.SmallSquare
        smallSquare.physicsBody?.contactTestBitMask = Collider.BigSquare
        smallSquare.physicsBody?.collisionBitMask = 0
        addChild(smallSquare)

        let bigSquare = SKSpriteNode(color: .purpleColor(), size: CGSize(width: 200, height: 200))
        bigSquare.zPosition = 1
        bigSquare.position = CGPoint(x: frame.midX, y: frame.midY)
        bigSquare.physicsBody = SKPhysicsBody(rectangleOfSize: bigSquare.size)
        bigSquare.physicsBody?.affectedByGravity = false
        bigSquare.physicsBody?.categoryBitMask = Collider.BigSquare
        bigSquare.physicsBody?.contactTestBitMask = Collider.SmallSquare
        bigSquare.physicsBody?.collisionBitMask = 0
        addChild(bigSquare)

    }

    func didBeginContact(contact: SKPhysicsContact) {

        print("Contact detected")
    }    
}

稍后，为了适本地检测某些物体之间的接触，您应该这样做:

func didBeginContact(contact: SKPhysicsContact) {

        var firstBody, 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 & Collider.SmallSquare) != 0 &&
            (secondBody.categoryBitMask & Collider.BigSquare != 0)) {

                print ("Contact detected")
        }

    }

但即使没有它，该消息也会在第一次启动游戏时打印出来，因为物理世界无论如何都会检测到接触。