Cannot detect collisions in spritekit - swift

Question

I am trying to build a game and my physics body contacts are not being detected. Can you pls help me? I have set the physicsWorldDelegate and categorybitmasks but cannot figure out what is wrong. The playground couldn't detect the collisions between the enemy and my avatar.
import SpriteKit
public class GameScene: SKScene, SKPhysicsContactDelegate {
let coronaSpeed: CGFloat = 80.0
let playerspeed: CGFloat = 155.0
var mask: SKSpriteNode?
var player: SKSpriteNode?
var mcorona: [SKSpriteNode] = []
var lastTouch: CGPoint? = nil
override public func didMove(to view: SKView) {
physicsWorld.contactDelegate = self
// Animations
player = childNode(withName: "player") as? SKSpriteNode
mask = childNode(withName: "mask") as? SKSpriteNode
mask!.run(SKAction.repeatForever(
SKAction.sequence([
SKAction.moveBy(x: 0, y: 10, duration: 0.45),
SKAction.moveBy(x: 0, y: -10, duration: 0.45)
]
)))
for child in self.children {
if child.name == "corona" {
if let child = child as? SKSpriteNode {
mcorona.append(child)
}
}
}
// </> Animations
}
override public func touchesBegan(_ touches: Set<UITouch>,with event: UIEvent?) { handleTouches(touches)
updatePlayer()
updateZombies()
}
override public func touchesMoved(_ touches: Set<UITouch>,with event: UIEvent?) { handleTouches(touches)
}
override public func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) { handleTouches(touches) }
fileprivate func handleTouches(_ touches: Set<UITouch>) { lastTouch = touches.first?.location(in: self) }
override public func didSimulatePhysics() {
if player != nil {
updatePlayer()
updateZombies()
}
}
fileprivate func shouldMove(currentPosition: CGPoint,
touchPosition: CGPoint) -> Bool {
guard let player = player else { return false }
return abs(currentPosition.x - touchPosition.x) > player.frame.width / 2 ||
abs(currentPosition.y - touchPosition.y) > player.frame.height / 2
}
fileprivate func updatePlayer() {
guard let player = player,
let touch = lastTouch
else { return }
let currentPosition = player.position
if shouldMove(currentPosition: currentPosition,
touchPosition: touch) {
updatePosition(for: player, to: touch, speed: playerspeed)
} else {
player.physicsBody?.isResting = true
}
}
func updateZombies() {
guard let player = player else { return }
let targetPosition = player.position
for corona in mcorona {
updatePosition(for: corona, to: targetPosition, speed: coronaSpeed)
}
}
func getDuration(pointA:CGPoint,pointB:CGPoint,speed:CGFloat)->TimeInterval{
let xDist = (pointB.x - pointA.x)
let yDist = (pointB.y - pointA.y)
let distance = sqrt((xDist * xDist) + (yDist * yDist));
let duration : TimeInterval = TimeInterval(distance/speed)
return duration
}
fileprivate func updatePosition(for sprite: SKSpriteNode, to target: CGPoint, speed: CGFloat) {
let currentPosition = sprite.position
let angle = CGFloat.pi + atan2(currentPosition.y - target.y, currentPosition.x - target.x)
let rotateAction = SKAction.rotate(toAngle: angle + (CGFloat.pi*0.5), duration: 0)
sprite.run(rotateAction)
//sprite.physicsBody?.isDynamic = true
let velocityX = speed * cos(angle)
let velocityY = speed * sin(angle)
let newVelocity = CGVector(dx: velocityX, dy: velocityY)
sprite.physicsBody?.velocity = newVelocity
sprite.physicsBody?.affectedByGravity = false
let moveToTouch = SKAction.move(to: CGPoint(x: target.x, y: target.y),duration: getDuration(pointA:currentPosition,pointB:target,speed:speed))
sprite.run(moveToTouch)
}
public func didBegin(_ contact: SKPhysicsContact) {
var firstBody: SKPhysicsBody
var secondBody: SKPhysicsBody
if contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask {
firstBody = contact.bodyA
secondBody = contact.bodyB
} else {
firstBody = contact.bodyB
secondBody = contact.bodyA
}
// Check contact
if firstBody.categoryBitMask == player?.physicsBody?.categoryBitMask &&
secondBody.categoryBitMask == mcorona[0].physicsBody?.categoryBitMask {
// Player & corona
gameOver(false)
} else if firstBody.categoryBitMask == player?.physicsBody?.categoryBitMask &&
secondBody.categoryBitMask == mask?.physicsBody?.categoryBitMask {
// Player & mask
gameOver(true)
}
}
fileprivate func gameOver(_ didWin: Bool) {
let resultScene = MenuScene(size: size, didWin: didWin, levelToSend: 2)
let transition = SKTransition.flipVertical(withDuration: 1.0)
view?.presentScene(resultScene, transition: transition)
}
}
Here is a GIF to my problem-
https://giphy.com/gifs/U7nmXZgVxNcCuvJc7j