Detect collision between sprites - ios

Question

I have a problem in my code.
I'm creating a Game and I need to have a sprite that can appear multiple times at the same time, to do so I created a class so I can do addChild(obstacle) multiple times and it will spawn one SKSpriteNode exactly similar to another.
My problem is that I want to check collision between my player and the obstacle but because it's from the same SKSpriteNode the computer can't know of which obstacle I'm talking about.
Here's how I created the player and the obstacle:
import SpriteKit
class Obstacle: SKSpriteNode {
init() {
let obstacleTexture = SKTexture(imageNamed: "obstacle")
super.init(texture: obstacleTexture, color: UIColor.clearColor(), size: CGSize(width: 80, height: 80))
}
required init(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
class GameScene: SKScene {
var player:SKSpriteNode!
override func didMoveToView(view: SKView) {
//player setup
let playerTexture = SKTexture(imageNamed: "player")
player = SKSpriteNode(texture: playerTexture)
player.position = CGPointMake(self.frame.size.width * 0.5, self.frame.size.height * 0.2)
}
//how I spawn an obstacle
func spawnObstacle() {
let obstacle = Obstacle()
//obstacle position setup
obstacle.position.x = CGFloat(arc4random()) % self.frame.size.width
obstacle.position.y = self.frame.size.height + 200
//random spin action setup
var rotateObstacle = SKAction.rotateByAngle(CGFloat(M_PI), duration: Double((drand48() + 1) * 0.75))
if random() % 2 == 0 {
rotateObstacle = SKAction.rotateByAngle(CGFloat(M_PI), duration: Double((drand48() + 1) * 0.75))
}else{
rotateObstacle = SKAction.rotateByAngle(-CGFloat(M_PI), duration: Double((drand48() + 1) * 0.75))
}
let rotateObstacleForever = SKAction.repeatActionForever(rotateObstacle)
//random move action setup
let moveObstacle = SKAction.moveTo(CGPointMake(CGFloat(arc4random()) % self.frame.size.width, -200), duration: Double((drand48() + 1) * 1.5))
//running the actions
obstacle.runAction(rotateObstacleForever)
obstacle.runAction(moveObstacle)
addChild(obstacle)
}
}
}
How to detect when the player collide with any obstacle?

Answer 1

To detect collisions you could use the SpriteKit physics.
Here you have 3 elements involved to hypothetical collisions:
The boundaries (or the field where live your player and where you
have your obstacles)
The player
The obstacles
Advice
Set this parameter to your debug phases to see physics objects boundaries :
skView.showsPhysics = true
An example of code (warning:- This code would be only a point to start to realize your physics, I don't know the rest of your project so your job will be to correct as you believe it's better for your objects):
enum CollisionTypes: UInt32 {
case Field = 1
case Player = 2
case Obstacle = 4
}
class GameScene: SKScene, SKPhysicsContactDelegate {
override func didMoveToView(view: SKView) {
self.physicsWorld.gravity = CGVectorMake(0, 0) // set your gravity value
self.physicsWorld.contactDelegate = self
let fieldBody = SKPhysicsBody.init(edgeLoopFromRect: self.frame)
self.physicsBody = fieldBody
self.physicsBody!.affectedByGravity = false
self.physicsBody!.usesPreciseCollisionDetection = true
self.physicsBody!.dynamic = true
self.physicsBody!.mass = 0.8
self.physicsBody!.friction = 0
self.physicsBody!.linearDamping = 0
self.physicsBody!.angularDamping = 0
self.physicsBody!.restitution = 0
self.physicsBody!.categoryBitMask = CollisionTypes.Field.rawValue
self.physicsBody!.contactTestBitMask = CollisionTypes.Player.rawValue
// Prepare the player
player.physicsBody = SKPhysicsBody(circleOfRadius: player.frame.width/2)
player.physicsBody!.affectedByGravity = false
player.physicsBody!.restitution = 0.0
player.physicsBody!.linearDamping = 0
player.physicsBody!.friction = 0.3
player.physicsBody!.dynamic = true
player.physicsBody!.mass = 0.2
player.physicsBody!.allowsRotation = false
player.physicsBody!.categoryBitMask = CollisionTypes.Player.rawValue
player.physicsBody!.contactTestBitMask = CollisionTypes.Field.rawValue | CollisionTypes.Obstacles.rawValue
player.physicsBody!.collisionBitMask = CollisionTypes.Field.rawValue | CollisionTypes.Obstacles.rawValue
//Prepare the obstacles (you must do it in your obstacle class)
obstacle.physicsBody = SKPhysicsBody(circleOfRadius: obstacle.frame.width/2)
obstacle.physicsBody!.affectedByGravity = false
obstacle.physicsBody!.restitution = 0.0
obstacle.physicsBody!.linearDamping = 0
obstacle.physicsBody!.friction = 0.3
obstacle.physicsBody!.dynamic = true
obstacle.physicsBody!.mass = 0.8
obstacle.physicsBody!.allowsRotation = true
obstacle.physicsBody!.categoryBitMask = CollisionTypes.Obstacle.rawValue
obstacle.physicsBody!.contactTestBitMask = CollisionTypes.Player.rawValue
obstacle.physicsBody!.collisionBitMask = CollisionTypes.Player.rawValue
}
func didBeginContact(contact: SKPhysicsContact) {
if (contact.bodyA.categoryBitMask == CollisionTypes.Player.rawValue &&
contact.bodyB.categoryBitMask == CollisionTypes.Obstacle.rawValue) {
print("contact between Player and Obstacle")
}
if (contact.bodyA.categoryBitMask == CollisionTypes.Player.rawValue &&
contact.bodyB.categoryBitMask == CollisionTypes.Field.rawValue) {
print("contact between Player and Field")
}
}
}