SpriteKit中的碰撞检测physicsBody

 //Adding SpriteKit physicsBody for collision detection
    missile.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:missile.size];
    missile.physicsBody.categoryBitMask = obstacleCategory;
    missile.physicsBody.dynamic = YES;
    missile.physicsBody.contactTestBitMask = shipCategory;
    missile.physicsBody.collisionBitMask = 0;
    missile.physicsBody.usesPreciseCollisionDetection = YES;
    missile.name = @"missile";

碰撞相关的解释如下

bird.physicsBody?.allowsRotation = false  //禁止旋转

bird.physicsBody?.categoryBitMask = birdCategory //设置小鸟物理体标示

bird.physicsBody?.contactTestBitMask = floorCategory | pipeCategory  //设置可以小鸟碰撞检测的物理体

CollisionBitmask：确定两个物体是否允许碰撞
如果希望A和B允许碰撞，则
A的CategoryBitmask与B的CollisionBitmask与运算结果为0
B的CategoryBitmask与A的CollisionBitmask与运算结果为0
否则A和B就不允许碰撞，接触后直接弹开

如果希望A和B发生碰撞检测，即调用onContactBegin，则
A的CategoryBitmask与B的ContactTestBitmask与运算结果不为0
B的CategoryBitmask与A的ContactTestBitmask与运算结果不为0

usesPreciseCollisionDetection一个布尔值,确定物理世界使用一个迭代的碰撞检测算法。

收缩.gif entrance.gif entracenImage.png