spritekit: unable to detect collision - ios

Question

so i tried to use skphysicscontact but when the "cat" and "spinnynode" collides there is no output from them, even when there is physical interaction
on another note, why can't the timer function work? it doesn't seem to call out the function at all.
please help, I'm a newbie. Thanks
import SpriteKit
import GameplayKit
import UIKit
import Foundation
struct physicsCollision {
static let cat: UInt32 = 1
static let spinnyNode: UInt32 = 2
}
class GameScene: SKScene, SKPhysicsContactDelegate {
var entities = [GKEntity]()
var graphs = [String : GKGraph]()
var catTimer = Timer()
var score = 0
private var lastUpdateTime : TimeInterval = 0
private var label : SKLabelNode?
private var spinnyNode : SKShapeNode?
let meow = SKAction.playSoundFileNamed("cat meow", waitForCompletion: false)
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
//random range
func randomInRange(lo: Float, hi : Float) -> Float{
return lo + Float(arc4random_uniform(UInt32(hi - lo + 1)))
}
//spawn cat
func spawnCat(){
// x coordinate between MinX (left) and MaxX (right):
let randomX = randomInRange(lo: Float(self.frame.minX + 5), hi: Float(self.frame.maxX + 5))
let startPoint = CGPoint(x: CGFloat(randomX), y: self.frame.height * 1.2)
let endPoint = CGPoint(x: CGFloat(randomX), y:self.frame.height * -0.5)
let cat = SKSpriteNode(imageNamed: "before right")
cat.name = "cat"
cat.setScale(0.3)
cat.position = startPoint
cat.zPosition = 1
cat.physicsBody = SKPhysicsBody(rectangleOf: CGSize(width: cat.size.width, height: cat.size.height))
cat.physicsBody?.affectedByGravity = false
cat.physicsBody?.categoryBitMask = physicsCollision.cat
cat.physicsBody?.contactTestBitMask = physicsCollision.spinnyNode
cat.physicsBody?.collisionBitMask = physicsCollision.spinnyNode
cat.physicsBody?.isDynamic = false
self.addChild(cat)
let moveCat = SKAction.move(to: endPoint, duration: 5)
let deleteCat = SKAction.removeFromParent()
let catSequence = SKAction.sequence([moveCat, meow, deleteCat])
cat.run(catSequence)
}
//contact func
func didBeginContact(contact:SKPhysicsContact){
var firstBody = SKPhysicsBody()
var secondBody = SKPhysicsBody()
if contact.bodyA.node?.name == "cat"
{
firstBody = contact.bodyA
secondBody = contact.bodyB
}
else{
firstBody = contact.bodyB
secondBody = contact.bodyA
}
if firstBody.node?.name == "cat" && (secondBody.node?.name)! == "skinnynode"{
print("contacted")
}
}
override func sceneDidLoad() {
self.physicsWorld.contactDelegate = self
self.lastUpdateTime = 0
//spawn cat at intervals,, time interval to decrease when points increase, use if loop
catTimer = Timer.init(timeInterval: 1 , target: self, selector: Selector(("cat")), userInfo: nil, repeats: true)
// Create shape node to use during mouse interaction
let w = (self.size.width + self.size.height) * 0.05
self.spinnyNode = SKShapeNode.init(rectOf: CGSize.init(width: w, height: w), cornerRadius: w * 0.5)
spinnyNode?.name = "spinnynode"
spinnyNode?.physicsBody = SKPhysicsBody(circleOfRadius: 0.5)
spinnyNode?.physicsBody?.affectedByGravity = false
spinnyNode?.zPosition = 1
spinnyNode?.physicsBody?.categoryBitMask = physicsCollision.spinnyNode
if let spinnyNode = self.spinnyNode{
spinnyNode.lineWidth = 1.5
spinnyNode.run(SKAction.repeatForever(SKAction.rotate(byAngle: CGFloat(Double.pi), duration: 1)))
spinnyNode.run(SKAction.sequence([SKAction.wait(forDuration: 0.5),
SKAction.fadeOut(withDuration: 0.3),
SKAction.removeFromParent()]))
}
//create score label
let scoreLabel = UILabel(frame: CGRect(x:((self.frame.height) * 0.5) , y:((self.frame.width) * 0.3), width: (self.frame.size.width)/3, height: 30))
scoreLabel.center = CGPoint(x: (self.frame.size.width)/1.6 , y: (self.frame.size.height)/2)
scoreLabel.textColor = UIColor.white
scoreLabel.text = "\(score)"
self.view?.addSubview(scoreLabel)
}
func touchDown(atPoint pos : CGPoint) {
if let n = self.spinnyNode?.copy() as! SKShapeNode? {
n.position = pos
n.strokeColor = SKColor.green
self.addChild(n)
}
}
func touchMoved(toPoint pos : CGPoint) {
if let n = self.spinnyNode?.copy() as! SKShapeNode? {
n.position = pos
n.strokeColor = SKColor.purple
self.addChild(n)
}
}
func touchUp(atPoint pos : CGPoint) {
if let n = self.spinnyNode?.copy() as! SKShapeNode? {
n.position = pos
n.strokeColor = SKColor.red
self.addChild(n)
}
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
spawnCat()
if let label = self.label {
label.run(SKAction.init(named: "Pulse")!, withKey: "fadeInOut")
}
for t in touches { self.touchDown(atPoint: t.location(in: self)) }
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
for t in touches { self.touchMoved(toPoint: t.location(in: self)) }
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
for t in touches { self.touchUp(atPoint: t.location(in: self)) }
}
override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
for t in touches { self.touchUp(atPoint: t.location(in: self)) }
}
override func update(_ currentTime: TimeInterval) {
// Called before each frame is rendered
// Initialize _lastUpdateTime if it has not already been
if (self.lastUpdateTime == 0) {
self.lastUpdateTime = currentTime
}
// Calculate time since last update
let dt = currentTime - self.lastUpdateTime
// Update entities
for entity in self.entities {
entity.update(deltaTime: dt)
}
self.lastUpdateTime = currentTime
}
}

Answer 1

You spelled the function wrong. It is never getting called. This is the correct protocol function name:
func didBegin(_ contact: SKPhysicsContact) {
// Your stuff here..
}
You can use autocomplete to avoid this problem. Start typing "didbegin" and you will have Xcode fill out the correct function:
As an aside:
Also, you are using hardcoded strings which can cause problems later on. Perhaps you could try using a constant value or a struct to avoid potential future spelling mistakes in strings:
let names = (cat: "cat", spinnynode: "spinnynode")
// cat.name = names.cat, etc...
func didBeginContact(contact:SKPhysicsContact){
// ...
if contact.bodyA.node?.name == names.cat
{
firstBody = contact.bodyA
secondBody = contact.bodyB
}
else{
firstBody = contact.bodyB
secondBody = contact.bodyA
}
if firstBody.node?.name == names.cat && secondBody.node!.name == names.spinnynode {
print("contacted")
}
}

Answer 2

Have you tried using the categoryBitMask method of the SKPhysicsContactDelegate? You may be able to fix your issue by going into the GameScene.sks file and assigning the Category Mask to a number other than the default. Do this for both of your bodies, but assign different values for each of the bodies.
Then, inside your GameScene.swift, your didBegin contact function might look something like this:
class GameScene: SKScene, SKPhysicsContactDelegate {
//set these values to the same number in your GameScene.sks file
let catCategory = 2
let skinnyNodeCategory = 3
func didBegin(_ contact: SKPhysicsContact) {
let bodyA = contact.bodyA
let bodyB = contact.bodyB
//check to see if the bodies in contact match
//the category mask numbers you defined
//here the conditional is set to say that either of the bodies
//in contact match the categoryBitMask number set in the GameScene.sks file
//using && may not work depending on how the categoryBitMask identifiers
//are assigned by the physicsContactDelegate
if bodyA.categoryBitMask == catCategory || bodyB.categoryBitMask == catCategory {
print("contacted")
}
}
}
override func update(_ currentTime: TimeInterval) {
// Called before each frame is rendered
}
}