why applyImpulse is not working in swift spritekit? - swift

Question

In my game, when user touches screen, a bullet is created with func fire() but nothing happen.
The following is my code:
private func fire(position: CGPoint) {
let bullet = SKShapeNode(circleOfRadius: 2)
bullet.strokeColor = SKColor.darkGray
bullet.fillColor = SKColor.darkGray
let posX = (position.x) * -1
let posY = (position.y) * -1
let pos = CGPoint(x: posX, y: posY)
let theta = atan2((pos.y - player.position.y), (pos.x - player.position.x))
let finalPos = CGPoint(x: (player.position.x) + (CGFloat(playerRadius) * cos(theta)), y: (player.position.y) + (CGFloat(playerRadius) * sin(theta)))
bullet.physicsBody = SKPhysicsBody(circleOfRadius: 2)
bullet.position = finalPos
bullet.physicsBody!.affectedByGravity = false
bullet.physicsBody!.isDynamic = false
bullet.physicsBody!.pinned = false
numberOfBullets += 1
bullet.name = String(numberOfBullets)
bullet.physicsBody!.collisionBitMask = bodyType.enemy.rawValue
bullet.physicsBody!.categoryBitMask = bodyType.bullet.rawValue
bullet.physicsBody!.contactTestBitMask = bodyType.enemy.rawValue
bullet.physicsBody!.usesPreciseCollisionDetection = true
world.addChild(bullet)
bulletForce(bullet: bullet)
}
private func bulletForce(bullet: SKShapeNode) {
let dx = Double((bullet.position.x - player.position.x))
let dy = Double((bullet.position.y - player.position.y))
let vector = CGVector(dx: dx, dy: dy)
bullet.physicsBody!.applyImpulse(vector)
}
Thanks in advance.

Answer 1

The reason it is failing is because you have isDynamic = false.
isDynamic means that forces can be applied to the body.
For more reading, please see:
read developer.apple.com/reference/spritekit/skphysicsbody