How do edit a sprite based on its name? - swift

Question

So in my game i have a function that spawns coins,they are given the name "coin", Now I have no way to reference the coins,example to kill them or move them.So what I'm trying to do is make a reference to be able to use in my code to just change its zPosition.
Everytime I run my app and have a function run that uses the coinRef [ex. to change the zPosition], the app crashes with the error:
'Thread 1 EXC_BAD_INSTRUCTION (code=EXC_1386_INVOP, subcode=0x0)'
Heres my code:
let coinRef: SKSpriteNode = self.childNodeWithName("coin")! as! SKSpriteNode
func hideCoins() {
coinRef.zPosition = -1
}
func showCoins() {
coinRef.zPosition = 101
}
func killCoins() {
coinRef.removeFromParent()
}

Answer 1

Looking at what you write
So in my game i have a function that spawns coins,they are given the name "coin"
it looks like there are multiple coins in your scene. As you can imagine a single name coin is not enough to univocally identify more then 1 coin :)
We'll need a way do identity multiple coins.
1. The Coin class
class Coin: SKSpriteNode {
private static var lastID: UInt = 0
let id:UInt
init() {
self.id = Coin.lastID++
let texture = SKTexture(imageNamed: "coin")
super.init(texture: texture, color: UIColor.clearColor(), size: texture.size())
self.name = "coin"
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
As you can see Coin has an internal mechanism to assign a new id to each new instance. You can use this id to reference the coins in your scene.
let coin0 = Coin()
coin0.id // 0
let coin1 = Coin()
coin1.id // 1
let coin2 = Coin()
coin2.id // 2
2. Managing your coins
class GameScene: SKScene {
func retrieveCoin(id:UInt) -> Coin? {
return children.filter { ($0 as? Coin)?.id == id }.first as? Coin
}
func hideCoin(id:UInt) {
retrieveCoin(id)?.hidden = true
}
func showCoin(id:UInt) {
retrieveCoin(id)?.hidden = true
}
func deleteCoin(id:UInt) {
retrieveCoin(id)?.removeFromParent()
}
}
The retrieveCoin method returns (if does exist) a coin with the specified id. Otherwise nil is returned.
The hideCoin and showCoin do change the hidden property to change its visibility.
Finally deleteCoin remove from the scene the Coin with the specified id.

Answer 2

Try this. Initialise coinRef before the didMoveToView function, and then give coinRef its value in the didMoveToView function.
class scene : SKScene {
let coinRef: SKSpriteNode = SKSpriteNode()
override func didMoveToView(view: SKView) {
coinRef: SKSpriteNode = self.childNodeWithName("coin")! as! SKSpriteNode
}
func hideCoins() {
coinRef.zPosition = -1
}
func showCoins() {
coinRef.zPosition = 101
}
func killCoins() {
coinRef.removeFromParent()
}
}