How to attach particles to moving object - ios

Question

I've created an PowerUpTrail.sks (particle thingy)
And I'm trying to attach it to a moving object
func SpawnPowerUp(){
let PowerUp = SKSpriteNode(imageNamed: "PowerUp.png")
let MinValue = self.size.width / 8
let MaxValue = self.size.width - 20
let SpawnPoint = UInt32(MaxValue - MinValue)
PowerUp.position = CGPoint(x: CGFloat(arc4random_uniform(SpawnPoint)), y: self.size.height - 100)
//Physics
PowerUp.physicsBody = SKPhysicsBody(rectangleOfSize: PowerUp.size)
PowerUp.physicsBody?.categoryBitMask = PhysicsCategory.PowerUp //Sätter unikt ID för Enemy, hämtat från PhysicsCategory som vi gjorde där uppe
PowerUp.physicsBody?.contactTestBitMask = PhysicsCategory.PowerUp //Kolla om Enemy nuddar Bullet
PowerUp.physicsBody?.affectedByGravity = false
PowerUp.physicsBody?.dynamic = true
let action = SKAction.moveToY(-128, duration: 5)
let actionDone = SKAction.removeFromParent()
PowerUp.runAction(SKAction.sequence([action, actionDone]))
PowerUp.runAction(SKAction.rotateByAngle(5, duration: 5))
/* this does not work!
let PowerUpTrail = SKEmitterNode(fileNamed: "PowerUpTrail.sks")
PowerUpTrail!.targetNode = self
PowerUpTrail!.position = PowerUp.position
self.addChild(PowerUpTrail!)
*/
self.addChild(PowerUp)
}
The particlethingy spawns but it doesnt follow the object. How do I solve this?

Answer 1

The simplest way to make one node's position track another is to use the node hierarchy: make the particle emitter a child node of the powerup sprite.
let powerUp = SKSpriteNode(imageNamed: "PowerUp.png")
// ...
let powerUpTrail = SKEmitterNode(fileNamed: "PowerUpTrail.sks")!
powerUpTrail.targetNode = self
powerUp.addChild(powerUpTrail)
(Also note some Swift style tips: initial-cap is conventionally for type names only; use initial-lowercase for variable names. And unwrap your optional from SKEmitterNode(fileNamed:) once when you create it instead of every time you use it thereafter.)