switching between enum states with touch - ios

Question

I have a simple player class like this:
enum State: Int {
case dead, alive, idle
}
class Player {
var playerSprite : SKSpriteNode
var currentState : State
init(passedInState: State) {
currentState = passedInState
self.playerSprite = SKSpriteNode(imageNamed: "playersprite.png")
switch currentState {
case .dead:
println("Player is dead")
case .alive:
println("Player is alive")
}
}
}
In my main class i create an instance of the Player class and try to change the players state by tapping on it in the touch method like so:
class GameScene: SKScene {
override func didMoveToView(view: SKView) {
let player1 = Player(passedInState: .alive)
self.addChild(player1.playerSprite)
player1.playerSprite.position = CGPointMake(100, 100)
}
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
for touch in touches {
let touch = touches.anyObject() as UITouch
let location = touch.locationInNode(self)
var locationSprites = nodesAtPoint(location)
for bla in locationSprites {
(bla as Player).currentState = .dead
}
}
}
I always get a crash when touching the Sprite. Do you have any idea why?

Answer 1

It seems there's a downcast failure, and in your code I see there are 2 forced donwcasts:
let touch = touches.anyObject() as UITouch
and
(bla as Player).currentState = .dead
I presume the error is in the last one, so I suggest setting a breakpoint and inspecting bla to check whether it's actually an instance of Player. Basing on your logic, if it can happen that it is not an instance of Player, I recommend using optional downcast:
if let player = bla as? Player {
player.currentState = .dead
}
The advantage is that if bla is not an instance of Player, the if block won't be executed, instead of making the app crash.
Comment follow up
If you want to do some custom processing when the player status changes, you can add a property observer to the currentState property of the Player class:
var currentState : State {
didSet {
switch currentState {
case .dead:
println("Player is dead")
case .alive:
println("Player is alive")
case .idle:
break
}
}
}