Implementing collision detections - ios

Question

Basically the game consists of a basket that the player moves across the screen, the aim of the game is for the player to catch balls falling from the top of the screen. I am currently trying to add collision detection between the balls and the basket, but am facing difficulties namely, implementing this collision detection. I am new to swift, sprite kit and app development, so please help. Any help would be appreciated. Another problem I am facing is that all the balls are falling in the centre of the screen. A line of code is supposed to execute when, the ball hits the basket and following that the ball should disappear, please help as I am new to Spritekit.
import SpriteKit
class GameScene: SKScene {
var basket = SKSpriteNode()
let actionMoveRight = SKAction.moveByX(50, y: 0, duration: 0.2)
let actionMoveLeft = SKAction.moveByX(-50, y: 0, duration: 0.2)
//let physicsBody = SKPhysicsBody(texture: , size: 3500)
override func didMoveToView(view: SKView) {
/* Setup your scene here */
self.physicsWorld.gravity = CGVectorMake(0.0, -0.5)
self.backgroundColor = SKColor.whiteColor()
basket = SKSpriteNode(imageNamed: "basket")
basket.setScale(0.5)
basket.position = CGPointMake(self.size.width/2, self.size.height/8)
basket.size.height = 50
basket.size.width = 75
self.addChild(basket)
let updateAction = SKAction.runBlock {
var choice = arc4random_uniform(3)
switch choice {
case 1 :
var ball1 = SKSpriteNode(imageNamed: "redBall")
ball1.position = CGPointMake(self.size.width/3, self.size.height)
ball1.setScale(0.5)
ball1.size.height = 20
ball1.size.width = 30
ball1.physicsBody = SKPhysicsBody(circleOfRadius: ball1.size.height / 2.75)
ball1.physicsBody!.dynamic = true
self.addChild(ball1)
println("0")
case 0 :
var ball2 = SKSpriteNode(imageNamed: "redBall")
ball2.position = CGPointMake(self.size.width/5, self.size.height)
ball2.setScale(0.5)
ball2.size.height = 20
ball2.size.width = 30
ball2.physicsBody = SKPhysicsBody(circleOfRadius: ball2.size.height / 2.75)
ball2.physicsBody!.dynamic = true
self.addChild(ball2)
println("1")
case 2 :
var ball3 = SKSpriteNode(imageNamed: "redBall")
ball3.position = CGPointMake(self.size.width*4/5, self.size.height)
ball3.setScale(0.5)
ball3.size.height = 20
ball3.size.width = 30
ball3.physicsBody = SKPhysicsBody(circleOfRadius: ball3.size.height / 2.75)
ball3.physicsBody!.dynamic = true
self.addChild(ball3)
println("2")
default :
println("Problem")
}
}
let waitDuration : NSTimeInterval = 1.0
let updateAndWaitAction = SKAction.sequence([updateAction,SKAction.waitForDuration(waitDuration)])
let repeatForeverAction = SKAction.repeatActionForever(updateAndWaitAction)
self.runAction(repeatForeverAction)
}
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
/* Called when a touch begins */
for touch: AnyObject in touches {
let location = touch.locationInNode(self)
if location.x > basket.position.x {
if basket.position.x < self.frame.maxX {
basket.runAction(actionMoveRight)
}
}
else {
if basket.position.x > self.frame.minX {
basket.runAction(actionMoveLeft)
}
}
}
}
override func update(currentTime: CFTimeInterval) {
}
}

Answer 1

For now you have a code that typically used in situations where user is taping something. You need to use BodyA & BodyB and assign a bitmasks to your nodes.
self.basket.physicsBody?.categoryBitMask = ColliderType.basket.rawValue
self.basket.physicsBody?.contactTestBitMask = ColliderType.ball1.rawValue
self.basket.physicsBody?.collisionBitMask = ColliderType.ball1.rawValue
self.basket.physicsBody?.contactTestBitMask = ColliderType.ball2.rawValue
self.basket.physicsBody?.collisionBitMask = ColliderType.ball2.rawValue
self.basket.physicsBody?.contactTestBitMask = ColliderType.ball3.rawValue
self.basket.physicsBody?.collisionBitMask = ColliderType.ball3.rawValue
And do that for every ball too. And then in func didBeginContact you should say to Xcode what to do, if you have an animation or something:
if (contact.bodyA.categoryBitMask == ColliderType.ball1.rawValue || contact.bodyB.categoryBitMask == ColliderType.ball1.rawValue) {
yourGameOverFunc()
}
if (contact.bodyA.categoryBitMask == ColliderType.ball2.rawValue || contact.bodyB.categoryBitMask == ColliderType.ball2.rawValue) {
yourGameOverFunc()
}
if (contact.bodyA.categoryBitMask == ColliderType.ball3.rawValue || contact.bodyB.categoryBitMask == ColliderType.ball3.rawValue) {
yourGameOverFunc()
}