greenBall.physicsBody?.categoryBitMask = GreenBallCategory //Category is GreenBall
greenBall.physicsBody?.contactTestBitMask = RedBarCategory | WallCategory //Contact will be detected when GreenBall make a contact with RedBar or a Wall (assuming that redBar's masks are already properly set)
greenBall.physicsBody?.collisionBitMask = GreenBallCategory | RedBallCategory | WallCategory //Collision will occur when GreenBall hits GreenBall,RedBall or hits a Wall

redBall.physicsBody?.categoryBitMask = RedBallCategory //Category is RedBall
redBall.physicsBody?.contactTestBitMask = GreenBarCategory | GreenBallCategory | WallCategory //Contact will be detected when RedBall make a contact with GreenBar,GreenBall or a Wall
redBall.physicsBody?.collisionBitMask = RedBallCategory | GreenBallCategory | WallCategory //Collision will occur when RedBall meets RedBall,GreenBall or hits a Wall

let borderBody = SKPhysicsBody(edgeLoopFromRect: self.frame)
self.physicsBody = borderBody
self.physicsBody?.friction = 0
borderBody.contactTestBitMask = RedBallCategory | GreenBallCategory //Contact will be detected when red or green ball hit the wall
borderBody.categoryBitMask = WallCategory
borderBody.collisionBitMask = RedBallCategory | GreenBallCategory // Collisions between RedBall GreenBall and a Wall will be detected

我建议您阅读约categoryBitMask的文档,这是一个面具,用于定义物理主体所属的类别：

Every physics body in a scene can be assigned to up to 32 different
categories,each corresponding to a bit in the bit mask. You define
the mask values used in your game. In conjunction with the
collisionBitMask and contactTestBitMask properties,you define which
physics bodies interact with each other and when your game is notified
of these interactions.

contactTestBitMask – 一个面具,用于定义哪些类别的物体与当前物理体引起交集通知.

When two bodies share the same space,each body’s category mask is
tested against the other body’s contact mask by performing a logical
AND operation. If either comparison results in a nonzero value,an
SKPhysicsContact object is created and passed to the physics world’s
delegate. For best performance,only set bits in the contacts mask for
interactions you are interested in.

collisionBitmask – 一个面具,用于定义哪些类别的物理物体可以与这个物理体碰撞.

When two physics bodies contact each other,a collision may occur.
This body’s collision mask is compared to the other body’s category
mask by performing a logical AND operation. If the result is a nonzero
value,this body is affected by the collision. Each body independently
chooses whether it wants to be affected by the other body. For
example,you might use this to avoid collision calculations that would
make negligible changes to a body’s velocity.

所以基本上,要设置所有这些,你应该问你自己的东西：

好吧,我有一个绿色的球,一个红色的球,和墙上的对象现场.在哪些机构我想要碰撞发生,或当我想要注册联系人？我想要一个绿色和一个红色的球相互碰撞并碰撞墙壁.不是问题我将首先正确设置类别,然后我将设置这样的碰撞位掩码：

greenBall.collisionBitMask = GreenBallCategory | RedBallCategory | WallCategory; //greenBall will collide with greenBall,redBall and a wall
redBall.collisionBitMask = GreenBallCategory | RedBallCategory | WallCategory

wall.collisionBitMask = GreenBall | RedBall

现在,我想检测一些联系人发生的时间(inBeginContact：method)…但是我不想收到所有可能的联系人的通知,而是要通知球之间的联系(球和墙之间的联系将被忽略).所以让我们设置contactTestBitMasks来实现这一点：

greenBall.contactTestBitMask = GreenBallCategory | RedBallCategory;
redBall.contactTestBitMask = GreenBallCategory | RedBallCategory;

就是这样重要的是当您不使用联系人检测时,不应设置contactTestBitMask.这是因为性能原因.如果您不需要碰撞检测,并且您只对检测到联系人感兴趣,可以设置collisionBitMask = 0.

重要：

确保您已设置物理世界的联系人委托以使用didBeginContact和didEndContact方法：

self.physicsWorld.contactDelegate = self; //where self is a current scene

希望这有帮助.