Swift Sprite Kit Physics Body: Ball slows down after applying an impulse - swift

Question

I am quite new to Swift and the Sprite Kit!
I tried to build a Pong game. Everything works well but the ball on which I am applying an impulse slows down really quickly!
I already turned off gravity, friction and damping and set the restitution of the ball and the scene to 1.
Here is my Code:
import SpriteKit
import GameplayKit
class GameScene: SKScene {
    
let player = SKShapeNode(rectOf: CGSize(width: 200, height: 30))
let enemy = SKShapeNode(rectOf: CGSize(width: 200, height: 30))
let ball = SKShapeNode(circleOfRadius: 10)
override func didMove(to view: SKView) {
let border = SKPhysicsBody(edgeLoopFrom: self.frame)
border.restitution = 1
border.friction = 0
border.angularDamping = 0
border.linearDamping = 0
self.physicsBody = border
scene?.physicsWorld.gravity = CGVector(dx: 0, dy: 0)
player.position = CGPoint(x:  0, y: -(scene?.size.height)! * 0.35)
player.fillColor = UIColor.white
player.strokeColor = UIColor.clear
self.addChild(player)
player.physicsBody = SKPhysicsBody(rectangleOf: CGSize(width: 200, height: 30))
player.physicsBody?.friction = 0
player.physicsBody?.isDynamic = false
player.physicsBody?.angularDamping = 0
player.physicsBody?.linearDamping = 0
player.physicsBody?.restitution = 1
player.physicsBody?.affectedByGravity = false
enemy.position = CGPoint(x: 0, y: (scene?.size.height)! * 0.35)
enemy.fillColor = UIColor.white
enemy.strokeColor = UIColor.clear
self.addChild(enemy)
enemy.physicsBody = SKPhysicsBody(rectangleOf: CGSize(width: 200, height: 30))
enemy.physicsBody?.friction = 0
enemy.physicsBody?.affectedByGravity = false
enemy.physicsBody?.linearDamping = 0
enemy.physicsBody?.angularDamping = 0
enemy.physicsBody?.isDynamic = false
ball.position = CGPoint(x: 0, y: 0)
ball.fillColor = UIColor.white
ball.strokeColor = UIColor.clear
ball.physicsBody?.angularDamping = 0
ball.physicsBody?.linearDamping = 0
ball.physicsBody?.friction = 0
ball.physicsBody?.restitution = 1
ball.physicsBody?.allowsRotation = false
ball.physicsBody?.affectedByGravity = true
ball.physicsBody = SKPhysicsBody(circleOfRadius: 10)
ball.physicsBody?.isDynamic = true
self.addChild(ball)
ball.physicsBody?.applyImpulse(CGVector(dx: -30, dy: -30))
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches {
let pos = touch.location(in: self)
player.position.x = pos.x
}
}
override func update(_ currentTime: TimeInterval) {
if ball.position.y >  0{
enemy.position.x = ball.position.x
}
}
}
Thank you already!

Answer 1

Be sure to always create your physics body before you change its properties
ball.physicsBody?.angularDamping = 0
ball.physicsBody?.linearDamping = 0
ball.physicsBody?.friction = 0
ball.physicsBody?.restitution = 1
ball.physicsBody?.allowsRotation = false
ball.physicsBody?.affectedByGravity = true
ball.physicsBody = SKPhysicsBody(circleOfRadius: 10) <----Needs to be first
ball.physicsBody?.isDynamic = true
self.addChild(ball)
ball.physicsBody?.applyImpulse(CGVector(dx: -30, dy: -30))