啟用節點衝突

首先，我們設定節點類別

let groundBody: UInt32 = 0x1 << 0
let boxBody: UInt32 = 0x1 << 1

然後新增 Ground 型別節點和 Box 型別節點。

let ground = SKSpriteNode(color: UIColor.cyanColor(), size: CGSizeMake(self.frame.width, 50))
ground.position = CGPointMake(CGRectGetMidX(self.frame), 100)
ground.physicsBody = SKPhysicsBody(rectangleOfSize: ground.size)
ground.physicsBody?.dynamic = false
ground.physicsBody?.categoryBitMask = groundBody
ground.physicsBody?.collisionBitMask = boxBody
ground.physicsBody?.contactTestBitMask = boxBody
    
addChild(ground)

// Add box type node

let box = SKSpriteNode(color: UIColor.yellowColor(), size: CGSizeMake(20, 20))
box.position = location
box.physicsBody = SKPhysicsBody(rectangleOfSize: box.size)
box.physicsBody?.dynamic = true
box.physicsBody?.categoryBitMask = boxBody
box.physicsBody?.collisionBitMask = groundBody | boxBody
box.physicsBody?.contactTestBitMask = boxBody
box.name = boxId
            
let action = SKAction.rotateByAngle(CGFloat(M_PI), duration:1)
            
box.runAction(SKAction.repeatActionForever(action))
            
self.addChild(box)