physicsBody collision with another physicsBody - xcode

Question

Okay, so I have a really specific problem and I hope I can help you. I will attach an image to clarify what I'm talking about.
redball.physicsBody is spawning above boss.physicsBody - falling (through) the boss. Colliding with whitebar.physicsBody - bouncing back up and once again colliding with boss.physicsBody. THIS time, i want to fire an event that notices when the ball is bouncing back up and hitting the boss.
Currently. Boss & Ball shares the same collisionBitMask, so that they can pass through each other. When the ball collides with the bar, I'm trying to add ball.physicsBody?.contactTestBitMask = PhysicsCategory.boss.rawValue to the ball. So that i can notice the collision on the way back up between ball & boss. However this does not seem to work.
Does anyone have a solution to this weird problem? Super thankful for some help.
Sidenote: If someone can figure out a clever title, let me know and ill edit it!
EDIT: Adding code
enum PhysicsCategory : UInt32 {
case bar = 1
case ball = 2
case boss = 4
case noCollision = 8
}
class GameScene: SKScene, SKPhysicsContactDelegate {
var score = Int()
var background = SKSpriteNode(imageNamed: "background.png")
var bar = SKSpriteNode(imageNamed: "bar.png")
var boss1 = SKSpriteNode(imageNamed: "boss1.png")
override func didMoveToView(view: SKView) {
self.scene?.size = CGSize(width: 640, height:1136)
physicsWorld.contactDelegate = self
background.position = CGPoint(x: self.frame.width / 2, y: self.frame.height / 2)
background.zPosition = -20
self.addChild(background)
bar.position = CGPoint(x: self.frame.width / 2, y: self.frame.height / 8)
bar.physicsBody = SKPhysicsBody(rectangleOfSize: CGSize(width: bar.size.width, height: bar.size.height))
bar.physicsBody?.categoryBitMask = PhysicsCategory.bar.rawValue
bar.physicsBody?.contactTestBitMask = PhysicsCategory.ball.rawValue
bar.physicsBody?.collisionBitMask = PhysicsCategory.bar.rawValue
bar.physicsBody?.affectedByGravity = false
bar.physicsBody?.dynamic = false
self.addChild(bar)
boss1.position = CGPoint(x: self.frame.width, y: self.frame.height - boss1.size.height / 2)
boss1.physicsBody = SKPhysicsBody(rectangleOfSize: CGSize(width: boss1.size.width, height: boss1.size.height))
boss1.physicsBody?.categoryBitMask = PhysicsCategory.boss.rawValue
boss1.physicsBody?.contactTestBitMask = PhysicsCategory.ball.rawValue
boss1.physicsBody?.collisionBitMask = PhysicsCategory.noCollision.rawValue
boss1.physicsBody?.affectedByGravity = false
boss1.physicsBody?.dynamic = false
boss1.zPosition = 5
self.addChild(boss1)
boss1.runAction(SKAction.moveToX(self.frame.width / 2, duration: 1))
let spawnBallsAction = SKAction.sequence([SKAction.waitForDuration(2), SKAction.runBlock(spawnBalls)])
self.runAction(SKAction.repeatActionForever(spawnBallsAction))
}
func didBeginContact(contact: SKPhysicsContact) {
let firstBody : SKPhysicsBody = contact.bodyA
let secondBody : SKPhysicsBody = contact.bodyB
if (firstBody.categoryBitMask & PhysicsCategory.bar.rawValue == PhysicsCategory.bar.rawValue &&
secondBody.categoryBitMask & PhysicsCategory.ball.rawValue == PhysicsCategory.ball.rawValue) {
CollisionWithBar(firstBody.node as! SKSpriteNode, ball: secondBody.node as! SKSpriteNode)
}
if (firstBody.categoryBitMask & PhysicsCategory.ball.rawValue == PhysicsCategory.ball.rawValue &&
secondBody.categoryBitMask & PhysicsCategory.boss.rawValue == PhysicsCategory.boss.rawValue) {
CollisionWithBoss(firstBody.node as! SKSpriteNode, boss: secondBody.node as! SKSpriteNode)
}
}
func CollisionWithBar(bar: SKSpriteNode, ball: SKSpriteNode) {
ball.physicsBody?.applyImpulse(CGVectorMake(0, 500))
ball.physicsBody?.contactTestBitMask = PhysicsCategory.boss.rawValue //Trying to solve the problem, aint working
}
func CollisionWithBoss(ball: SKSpriteNode, boss: SKSpriteNode) {
NSLog("Ball hit the boss")
}
func spawnBalls(){
let ball = SKSpriteNode(imageNamed: "ball.png")
let MinValue = self.frame.width / 8
let MaxValue = self.frame.width - 20
let SpawnPoint = UInt32(MaxValue - MinValue)
ball.position = CGPoint(x: CGFloat(arc4random_uniform(SpawnPoint)), y: self.frame.height - 128)
ball.zPosition = 50
//Physics
ball.physicsBody = SKPhysicsBody(circleOfRadius: ball.frame.height / 2)
ball.physicsBody?.categoryBitMask = PhysicsCategory.ball.rawValue
ball.physicsBody?.contactTestBitMask = PhysicsCategory.bar.rawValue
ball.physicsBody?.collisionBitMask = PhysicsCategory.noCollision.rawValue
ball.physicsBody?.affectedByGravity = true
ball.physicsBody?.dynamic = true
self.addChild(ball)
}

Answer 1

This is how contacts should be done:
Upon creating a ball set the contact category to this:(which you have)
ball.physicsBody?.contactTestBitMask = PhysicsCategory.bar.rawValue
Make sure the boss contacts nobody:
boss1.physicsBody?.contactTestBitMask = PhysicsCategory.noCollision.rawValue
Then on Contact, you want to do this:
func didBeginContact(contact: SKPhysicsContact) {
let firstBody : SKPhysicsBody = (contact.bodyA.categoryBitMask <= contact.bodyB.categoryBitMask) ? contact.bodyA : contact.bodyB
let secondBody : SKPhysicsBody = (contact.bodyA.categoryBitMask >= contact.bodyB.categoryBitMask) ? contact.bodyA : contact.bodyB
if (firstBody.categoryBitMask & PhysicsCategory.bar.rawValue == PhysicsCategory.bar.rawValue &&
secondBody.categoryBitMask & PhysicsCategory.ball.rawValue == PhysicsCategory.ball.rawValue) {
//This should be inside CollisionWithBar
ball.physicsBody?.contactTestBitMask = PhysicsCategory.bar.rawValue | PhysicsCategory.boss.rawValue
//the ball has hit the bar, so lets enable hitting on the boss
//normally we would only want to do this once, but since this is
//tiny, it would be more time to wrap it in ifs and putting guards on it
boss1.physicsBody?.contactTestBitMask = PhysicsCategory.ball.rawValue
CollisionWithBar(firstBody.node as! SKSpriteNode, ball: secondBody.node as! SKSpriteNode)
}
if (firstBody.categoryBitMask & PhysicsCategory.ball.rawValue == PhysicsCategory.ball.rawValue &&
secondBody.categoryBitMask & PhysicsCategory.boss.rawValue == PhysicsCategory.boss.rawValue) {
//This should be inside CollisionWithBoss
ball.physicsBody?.contactTestBitMask = PhysicsCategory.bar.rawValue
CollisionWithBoss(firstBody.node as! SKSpriteNode, boss: secondBody.node as! SKSpriteNode)
}
}
Which basically says, if the ball hits the bar, enable boss hitting, if the ball hits the boss, disable boss hitting
Edit: Upon the realization of having multiple balls, we have to change some things
Make sure the boss contacts ball upon creation again:
boss1.physicsBody?.contactTestBitMask = PhysicsCategory.ball.rawValue
Now we need to create a new category
enum PhysicsCategory : UInt32 {
case bar = 1
case ball = 2
case boss = 4
case noCollision = 8
case initialBall = 16
}
In the beginning, assign the category of ball to this:
ball.physicsBody?.categoryBitMask = initialBall
Then your CollissionWithBar will look like this:
func CollisionWithBar(bar: SKSpriteNode, ball: SKSpriteNode) {
ball.physicsBody?.applyImpulse(CGVectorMake(0, 500))
ball.physicsBody?.contactTestBitMask = PhysicsCategory.bar.rawValue | PhysicsCategory.boss.rawValue
ball.physicsBody?.categoryBitMask = PhysicsCategory.ball.rawValue
}
And your CollissionWithBolls will look like this:
func CollisionWithBoss(ball: SKSpriteNode, boss: SKSpriteNode) {
ball.physicsBody?.contactTestBitMask = PhysicsCategory.bar.rawValue
}
Finally, on Contact, you want to do this:
func didBeginContact(contact: SKPhysicsContact) {
let firstBody : SKPhysicsBody = (contact.bodyA.categoryBitMask <= contact.bodyB.categoryBitMask) ? contact.bodyA : contact.bodyB
let secondBody : SKPhysicsBody = (contact.bodyA.categoryBitMask >= contact.bodyB.categoryBitMask) ? contact.bodyA : contact.bodyB
if (firstBody.categoryBitMask & PhysicsCategory.bar.rawValue == PhysicsCategory.bar.rawValue &&
secondBody.categoryBitMask & PhysicsCategory.ball.rawValue == PhysicsCategory.ball.rawValue) {
CollisionWithBar(firstBody.node as! SKSpriteNode, ball: secondBody.node as! SKSpriteNode)
}
if (firstBody.categoryBitMask & PhysicsCategory.ball.rawValue == PhysicsCategory.ball.rawValue &&
secondBody.categoryBitMask & PhysicsCategory.boss.rawValue == PhysicsCategory.boss.rawValue) {
CollisionWithBoss(firstBody.node as! SKSpriteNode, boss: secondBody.node as! SKSpriteNode)
}
}