swift shooting objects from circle shape - swift

Question

I have a circle in the middle and I need to fire bullets in direction opposite to where I touch and come out from the player, I wrote the following code but nothing happen
private func fire(position: CGPoint) {
let bullet = SKShapeNode(circleOfRadius: 2)
bullet.strokeColor = SKColor.darkGray
bullet.fillColor = SKColor.darkGray
bullet.physicsBody = SKPhysicsBody(circleOfRadius: 2)
let posX = (position.x) * -1
let posY = (position.y) * -1
let pos = CGPoint(x: posX, y: posY)
bullet.position = pos
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, position: position)
}
private func bulletForce(bullet: SKShapeNode, position: CGPoint) {
let ddx = Double((bullet.position.x - position.x))
let ddy = Double((bullet.position.y - position.y))
let degree = atan2(ddy, ddx) * (180.0 / M_PI)
let magnitude = 900.0
let angle = degree
let dx = magnitude * cos(angle)
let dy = magnitude * sin(angle)
let vector = CGVector(dx: dx,dy: dy)
bullet.physicsBody?.applyForce(vector)
//bullet.run(fire, withKey: "firing\(bullet.name)")
}
EDIT ::
This solved the problem thanks to the aid from the accepted answer
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 dx = cos(theta) / 4
let dy = sin(theta) / 4
world.addChild(bullet)
let vector = CGVector(dx: dx, dy: dy)
bullet.physicsBody!.applyImpulse(vector)
where theta is the angle i want the bullet to go to and here it is
Note::
The player is in the middle ( circle ).
The posX and posY are the x and y coordinates where the user touched and they are multiplied by -1 to get the opposite direction where my bullet will be placed.
The angle theta is then calculated using the atan2 function that instead of positioning my bullet away from the player ( circle ), it will position it at the edge of circle.

Answer 1

Have you tried switching isDynamic from "false" to "true"? Also, try adding GCVector(dx: 1.0 * dx, dy: 1.0 * dy)