use two sprite objects at the same time with single touch? - ios

Question

Currently, I can only use one at a time, and not make the two paddles (one on each side of the screen) act independently when different finger movements are used with each one. Here is the class. Any ideas?
let BallCategoryName = "ball"
let GameMessageName = "gameMessage"
let BallCategory : UInt32 = 0x1 << 0
let LeftCategory : UInt32 = 0x1 << 1
let BlockCategory : UInt32 = 0x1 << 2
let PaddleCategory : UInt32 = 0x1 << 3
let BorderCategory : UInt32 = 0x1 << 4
class GameScene: SKScene, SKPhysicsContactDelegate {
var isFingerOnPaddleL = false
var isFingerOnPaddleR = false
override func didMove(to view: SKView) {
super.didMove(to: view)
let borderBody = SKPhysicsBody(edgeLoopFrom: self.frame)
borderBody.friction = 0
self.physicsBody = borderBody
physicsWorld.gravity = CGVector(dx: 0.0, dy: 0.0)
physicsWorld.contactDelegate = self
let ball = childNode(withName: BallCategoryName) as! SKSpriteNode
ball.physicsBody!.applyImpulse(CGVector(dx: 2.0, dy: -2.0))
let paddleL = childNode(withName: "paddleL") as! SKSpriteNode
//let paddleR = childNode(withName: "paddleR") as! SKSpriteNode
let leftRect = CGRect(x: frame.origin.x, y: frame.origin.y, width: 1, height: frame.size.height)
let left = SKNode()
left.physicsBody = SKPhysicsBody(edgeLoopFrom: leftRect)
addChild(left)
left.physicsBody!.categoryBitMask = LeftCategory
ball.physicsBody!.categoryBitMask = BallCategory
paddleL.physicsBody!.categoryBitMask = PaddleCategory
borderBody.categoryBitMask = BorderCategory
ball.physicsBody!.contactTestBitMask = LeftCategory
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
let touch = touches.first
let touchLocation = touch!.location(in: self)
if let body = physicsWorld.body(at: touchLocation) {
if body.node!.name == "paddleL" {
print("Began touch on paddleL")
isFingerOnPaddleL = true
}
else if body.node!.name == "paddleR" {
print("Began touch on paddleR")
isFingerOnPaddleR = true
}
}
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
// 1
if isFingerOnPaddleL {
// 2
let touch = touches.first
let touchLocation = touch!.location(in: self)
let previousLocation = touch!.previousLocation(in: self)
// 3
let paddle = childNode(withName: "paddleL") as! SKSpriteNode
// 4
var paddleY = paddle.position.y + (touchLocation.y - previousLocation.y)
// 5
paddleY = max(paddle.size.height/2, paddleY)
paddleY = min(size.height - paddle.size.height/2, paddleY)
// 6
paddle.position = CGPoint(x: paddle.position.x, y: paddleY)
}
else if isFingerOnPaddleR {
// 2
let touch = touches.first
let touchLocation = touch!.location(in: self)
let previousLocation = touch!.previousLocation(in: self)
// 3
let paddle = childNode(withName: "paddleR") as! SKSpriteNode
// 4
var paddleY = paddle.position.y + (touchLocation.y - previousLocation.y)
// 5
paddleY = max(paddle.size.height/2, paddleY)
paddleY = min(size.height - paddle.size.height/2, paddleY)
// 6
paddle.position = CGPoint(x: paddle.position.x, y: paddleY)
}
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
if (isFingerOnPaddleL == true) {
isFingerOnPaddleL = false
}
else if (isFingerOnPaddleR == true) {
isFingerOnPaddleR = false
}
}
func didBegin(_ contact: SKPhysicsContact) {
// 1
var firstBody: SKPhysicsBody
var secondBody: SKPhysicsBody
// 2
if contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask {
firstBody = contact.bodyA
secondBody = contact.bodyB
} else {
firstBody = contact.bodyB
secondBody = contact.bodyA
}
// 3
if firstBody.categoryBitMask == BallCategory && secondBody.categoryBitMask == LeftCategory {
print("Hit left. First contact has been made.")
}
}
}

Answer 1

You can process the paddles independently by tracking each touch throughout its lifecycle (began/moved/ended). First, define a dictionary with the touch object as the key and the node's name as the value
var touchTracker:[UITouch:String] = [:]
then in touchesBegan, store the name of paddle(s) touched by the user
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches {
let touchLocation = touch.location(in: self)
let node = atPoint(touchLocation)
if let name = node.name {
if name == "paddleL" {
print("Began touch on paddleL")
touchTracker[touch] = name
}
else if name == "paddleR" {
print("Began touch on paddleR")
touchTracker[touch] = name
}
}
}
}
In touchesMoved, use the touch object to retrieve the node's name from the dictionary, and use the name to access the appropriate paddle.
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches {
let touchLocation = touch.location(in: self)
if let name = touchTracker[touch] {
if let paddle = childNode(withName: name) as? SKSpriteNode {
// Move a paddle
paddle.position = CGPoint(x:paddle.position.x, y:touchLocation.y)
}
}
}
}
Lastly, remove the touch/name from the dictionary when a touch ends.
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches {
if touchTracker[touch] != nil {
touchTracker.removeValue(forKey: touch)
}
}
}