My game is crashing after comes back from GameOverScene - ios

Question

I'm creating my first Game and it crashes after come back from GameOverScene. This are the part that gives me the error:
// GameScene.swift
// Test_Crash_1
import SpriteKit
struct global {
static var wheelRotPlat2 = SKShapeNode(circleOfRadius: 400)
static var button : SKShapeNode = SKShapeNode()
static var actualPlayer : String = String()
static let btnNextPlayer = SKShapeNode(circleOfRadius: 70)
}
class GameScene: SKScene {
deinit {
print("The GameScene has been removed from memory")
}
override func didMoveToView(view: SKView) {
let buttonDice = SKShapeNode(rectOfSize: (CGSizeMake(40,40)), cornerRadius: 5)
global.button = buttonDice
global.button.position = CGPoint(x: (CGRectGetMidX(self.frame)-400), y:(CGRectGetMidY(self.frame)-350))
global.button.fillColor = UIColor(red: 0.2, green: 1.0, blue: 0.2, alpha: 0.8)
global.button.name = "button"
global.button.zPosition = 1
addChild(global.button)
global.wheelRotPlat2.addChild(global.btnNextPlayer)
global.btnNextPlayer.name = "btnNextPlayer"
} // end didMoveToView
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
//func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
let touch = touches //as! Set<UITouch>
let location = touch.first!.locationInNode(self)
let node = self.nodeAtPoint(location)
if (node.name == "button") {
self.removeAllActions()
self.removeAllChildren()
let reveal = SKTransition.flipHorizontalWithDuration(0.5)
let gameOverScene = GameOverScene(size: self.size, player: global.actualPlayer)
self.view?.presentScene(gameOverScene, transition: reveal)
}
} // End func touchesBegan
} // end GameScene
And the GameOverScene file:
// GameOverScene.swift
// Test_Crash_1
import Foundation
import SpriteKit
class GameOverScene: SKScene {
init(size: CGSize, player: String) {
super.init(size: size)
backgroundColor = SKColor.whiteColor()
runAction(SKAction.sequence([
SKAction.waitForDuration(3.0),
SKAction.runBlock() {
let reveal = SKTransition.flipHorizontalWithDuration(0.5)
let scene = GameScene(size: size)
self.view?.presentScene(scene, transition:reveal)
}
]))
} // end init(size
required init(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
} // end GameOverScene
The error is well the known:
Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Attemped to add a SKNode which already has a parent: SKShapeNode name:'btnNextPlayer'
This example has just a green button that takes me to the GameOverScene. When it returns the game crashes.
I don't understand why it happens in this case.
Can anyone tell me why this happens and how to fix it?

Answer 1

The error tells you what is happening, you are adding a node to another node, but the node already has a parent. This is why using globals is a bad idea and should almost never be used. You have a button that is global. It is attached to GameScene, lets call GameScene1. You then call Gameover. Now you call a new GameScene, called GameScene2. Since you are not managing your memory correctly because of things like global variables, GameScene1 still exists. Well button is still attached to GameScene1, so when you try to add it to GameScene2, XCode says "No, this node has a parent, go fix yo stuff". Try to not use global data, and you should see less problems like this.
Edit:
As #Whirlwind pointed out, the issue is in the global item global.wheelRotPlat2 that is causing the problem.
global.wheelRotPlat2.addChild(global.btnNextPlayer) is being called every time a GameScene is moved to a view, and since you never remove the btnNextPlayer from its parent when you kill your 1st Scene, when you create your 2nd Scene, the global.btnNextPlayer will try to reattach to the same exact parent again (global.wheelRotPlat2), which is causing your problem.