app keeps crashing , Terminating app due to uncaught exception 'NSInvalidArgumentException' - ios

Question

I am creating a game where random objects fall in random places and there is a ball with a fixed y-axis and keeps moving along the x-axis , and it has to move throw the objects , and i am trying to count the scores and the way i do it is i created a physics object and it is places in the same y-axis as the ball , and when the objects collide the score function should be called and increment the score by 1, but for some reason the app keeps crashing and it gives me this error.
2015-07-13 01:23:17.242 WalkRun[26792:3773366] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Attemped to add a SKNode which already has a parent: <SKSpriteNode> name:'(null)' texture:[<SKTexture> 'shortwall' (60 x 60)] position:{30, 768} size:{60, 60} rotation:0.00'
*** First throw call stack:
(
0 CoreFoundation 0x00000001073c33f5 __exceptionPreprocess + 165
1 libobjc.A.dylib 0x00000001092eabb7 objc_exception_throw + 45
2 CoreFoundation 0x00000001073c332d +[NSException raise:format:] + 205
3 SpriteKit 0x0000000107ebfaf6 -[SKNode addChild:] + 111
4 WalkRun 0x00000001071c8c44 _TFC7WalkRun9PlayScene10leftObjectfS0_FT_T_ + 2868
5 WalkRun 0x00000001071c7ddc _TFC7WalkRun9PlayScene10randObjectfS0_FT_T_ + 236
6 WalkRun 0x00000001071c8102 _TToFC7WalkRun9PlayScene10randObjectfS0_FT_T_ + 34
7 Foundation 0x0000000107a39fd4 __NSFireTimer + 83
8 CoreFoundation 0x000000010732b4e4 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 20
9 CoreFoundation 0x000000010732b0a5 __CFRunLoopDoTimer + 1045
10 CoreFoundation 0x00000001072ee3dd __CFRunLoopRun + 1901
11 CoreFoundation 0x00000001072eda06 CFRunLoopRunSpecific + 470
12 GraphicsServices 0x000000010e7569f0 GSEventRunModal + 161
13 UIKit 0x0000000108046550 UIApplicationMain + 1282
14 WalkRun 0x00000001071d54ce top_level_code + 78
15 WalkRun 0x00000001071d550a main + 42
16 libdyld.dylib 0x0000000109ad9145 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
and this is my code:
//
// PlayScene.swift
// WalkRun
//
// Created by naeim on 7/10/15.
// Copyright (c) 2015 naeim. All rights reserved.
//
import Foundation
import SpriteKit
class PlayScene: SKScene, SKPhysicsContactDelegate{
var ball = SKSpriteNode(imageNamed: "ball")
var wall = SKNode()
var wallRight = SKNode()
var wallMiddle = SKNode()
var ballSpeed = CGFloat()
var bigWall = SKSpriteNode(imageNamed: "shortwall")
var tallWall = SKSpriteNode(imageNamed: "tallwall")
var ballGroup:UInt32 = 1
var objectGroup:UInt32 = 2
var gapGroup:UInt32 = 3
var gameOver = 0
var movingObjects = SKNode()
var score = 0
var scoreLabel = SKLabelNode()
override func didMoveToView(view: SKView) {
self.physicsWorld.contactDelegate = self
backgroundColor = UIColor(hex: 0x80d9ff)
self.physicsWorld.gravity = CGVectorMake(-9,0)
self.addChild(movingObjects)
//creating the ball
ball.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMinY(self.frame) + self.ball.size.height * 2)
ball.physicsBody = SKPhysicsBody(circleOfRadius: self.ball.size.width / 2)
ball.zPosition = 10
//let the ball rotate forever
ballSpeed = 3
let rotateAction = SKAction.rotateByAngle(ballSpeed, duration: 1)
let repeatAction = SKAction.repeatActionForever(rotateAction)
ball.runAction(repeatAction)
ball.physicsBody?.categoryBitMask = ballGroup
ball.physicsBody?.collisionBitMask = objectGroup
ball.physicsBody?.contactTestBitMask = objectGroup
self.addChild(ball)
//creating the wall of the left
wall.position = CGPointMake(CGRectGetMinX(self.frame),CGRectGetMinY(self.frame))
wall.physicsBody = SKPhysicsBody(rectangleOfSize: CGSizeMake(2, self.frame.size.height * 2.0))
wall.physicsBody?.dynamic = false
wall.physicsBody?.categoryBitMask = objectGroup
self.addChild(wall)
//creating the wall of the right
wallRight.position = CGPointMake(CGRectGetMaxX(self.frame), CGRectGetMinY(self.frame))
wallRight.physicsBody = SKPhysicsBody(rectangleOfSize: CGSizeMake(2, self.frame.size.height * 2.0))
wallRight.physicsBody?.dynamic = false
wallRight.physicsBody?.categoryBitMask = objectGroup
self.addChild(wallRight)
//creating the middle wall that objects pass by
wallMiddle.position = CGPointMake(CGRectGetMinX(self.frame), CGRectGetMinY(self.frame))
wallMiddle.physicsBody = SKPhysicsBody(rectangleOfSize: CGSizeMake(self.frame.size.width, 1))
wallMiddle.physicsBody?.dynamic = false
wallMiddle.physicsBody?.categoryBitMask = gapGroup
wallMiddle.physicsBody?.collisionBitMask = gapGroup
wallMiddle.physicsBody?.contactTestBitMask = objectGroup
self.addChild(wallMiddle)
//creating the label
scoreLabel.fontName = "Helvetica"
scoreLabel.fontSize = 60
scoreLabel.text = "0"
scoreLabel.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame) + 70 )
self.addChild(scoreLabel)
var timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: Selector("randObject"), userInfo: nil, repeats: true)
var timerObjects = NSTimer.scheduledTimerWithTimeInterval(0.01, target: self, selector: Selector("checkObjectPlace"), userInfo: nil, repeats: true)
}
func checkObjectPlace(){
}
//function to randomly choose which object
func randObject(){
if gameOver == 0{
var rand = arc4random_uniform(6)+1
switch(rand){
case 1:
leftObject()
case 2:
middleObject()
case 3:
rightObject()
case 4:
LeftAndMiddleObject()
case 5:
rightAndLeftObject()
case 6:
rightAndMiddleObject()
default:
println("error !! non a number other than 0, 1, 2 has been choosen .")
}
}
}
//function to create the left objects
func leftObject(){
var rand = arc4random_uniform(2) + 1
if rand == 1
{
bigWall.position = CGPointMake(CGRectGetMinX(self.frame) + bigWall.size.width / 2, CGRectGetMaxY(self.frame))
var moveObjects = SKAction.moveByX(0, y: -self.frame.size.height * 2, duration: NSTimeInterval(self.frame.size.height / 100))
var removeObjects = SKAction.removeFromParent()
var moveAndRemoveObjects = SKAction.sequence([moveObjects,removeObjects])
bigWall.runAction(moveAndRemoveObjects)
bigWall.physicsBody = SKPhysicsBody(rectangleOfSize: bigWall.size)
bigWall.physicsBody?.dynamic = false
bigWall.physicsBody?.categoryBitMask = objectGroup
movingObjects.addChild(bigWall)
}
else
{
tallWall.position = CGPointMake(CGRectGetMinX(self.frame) + tallWall.size.width / 2, CGRectGetMaxY(self.frame))
var moveObjects = SKAction.moveByX(0, y: -self.frame.size.height * 2, duration: NSTimeInterval(self.frame.size.height / 100))
var removeObjects = SKAction.removeFromParent()
var moveAndRemoveObjects = SKAction.sequence([moveObjects,removeObjects])
tallWall.runAction(moveAndRemoveObjects)
tallWall.physicsBody = SKPhysicsBody(rectangleOfSize: tallWall.size)
tallWall.physicsBody?.dynamic = false
tallWall.physicsBody?.categoryBitMask = objectGroup
movingObjects.addChild(tallWall)
}
}
//function to create the middle objects
func middleObject(){
var rand = arc4random_uniform(2) + 1
if rand == 1
{
var bigWall = SKSpriteNode(imageNamed: "shortwall")
bigWall.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMaxY(self.frame))
var moveObjects = SKAction.moveByX(0, y: -self.frame.size.height * 2, duration: NSTimeInterval(self.frame.size.height / 100))
var removeObjects = SKAction.removeFromParent()
var moveAndRemoveObjects = SKAction.sequence([moveObjects,removeObjects])
bigWall.runAction(moveAndRemoveObjects)
bigWall.physicsBody = SKPhysicsBody(rectangleOfSize: bigWall.size)
bigWall.physicsBody?.dynamic = false
bigWall.physicsBody?.categoryBitMask = objectGroup
movingObjects.addChild(bigWall)
}
else
{
var tallWall = SKSpriteNode(imageNamed: "tallwall")
tallWall.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMaxY(self.frame))
var moveObjects = SKAction.moveByX(0, y: -self.frame.size.height * 2, duration: NSTimeInterval(self.frame.size.height / 100))
var removeObjects = SKAction.removeFromParent()
var moveAndRemoveObjects = SKAction.sequence([moveObjects,removeObjects])
tallWall.runAction(moveAndRemoveObjects)
tallWall.physicsBody = SKPhysicsBody(rectangleOfSize: tallWall.size)
tallWall.physicsBody?.dynamic = false
tallWall.physicsBody?.categoryBitMask = objectGroup
movingObjects.addChild(tallWall)
}
}
//function to create the right objects
func rightObject(){
var rand = arc4random_uniform(2) + 1
if rand == 1
{
var bigWall = SKSpriteNode(imageNamed: "shortwall")
bigWall.position = CGPointMake(CGRectGetMaxX(self.frame) - bigWall.size.width / 2, CGRectGetMaxY(self.frame))
var moveObjects = SKAction.moveByX(0, y: -self.frame.size.height * 2, duration: NSTimeInterval(self.frame.size.height / 100))
var removeObjects = SKAction.removeFromParent()
var moveAndRemoveObjects = SKAction.sequence([moveObjects,removeObjects])
bigWall.runAction(moveAndRemoveObjects)
bigWall.physicsBody = SKPhysicsBody(rectangleOfSize: bigWall.size)
bigWall.physicsBody?.dynamic = false
bigWall.physicsBody?.categoryBitMask = objectGroup
movingObjects.addChild(bigWall)
}
else
{
var tallWall = SKSpriteNode(imageNamed: "tallwall")
tallWall.position = CGPointMake(CGRectGetMaxX(self.frame) - tallWall.size.width / 2, CGRectGetMaxY(self.frame))
var moveObjects = SKAction.moveByX(0, y: -self.frame.size.height * 2, duration: NSTimeInterval(self.frame.size.height / 100))
var removeObjects = SKAction.removeFromParent()
var moveAndRemoveObjects = SKAction.sequence([moveObjects,removeObjects])
tallWall.runAction(moveAndRemoveObjects)
tallWall.physicsBody = SKPhysicsBody(rectangleOfSize: tallWall.size)
tallWall.physicsBody?.dynamic = false
tallWall.physicsBody?.categoryBitMask = objectGroup
movingObjects.addChild(tallWall)
if ball.position.x == tallWall.position.x{
scoreIncrement()
}
}
}
//function to create a right and left object
func rightAndLeftObject(){
var rand = arc4random_uniform(2) + 1
if rand == 1
{
var bigWall = SKSpriteNode(imageNamed: "shortwall")
var tallWall = SKSpriteNode(imageNamed: "tallwall")
tallWall.position = CGPointMake(CGRectGetMinX(self.frame) + tallWall.size.width / 2, CGRectGetMaxY(self.frame))
bigWall.position = CGPointMake(CGRectGetMaxX(self.frame) - bigWall.size.width / 2, CGRectGetMaxY(self.frame))
var moveObjects = SKAction.moveByX(0, y: -self.frame.size.height * 2, duration: NSTimeInterval(self.frame.size.height / 100))
var removeObjects = SKAction.removeFromParent()
var moveAndRemoveObjects = SKAction.sequence([moveObjects,removeObjects])
bigWall.runAction(moveAndRemoveObjects)
tallWall.runAction(moveAndRemoveObjects)
tallWall.physicsBody = SKPhysicsBody(rectangleOfSize: tallWall.size)
tallWall.physicsBody?.dynamic = false
bigWall.physicsBody = SKPhysicsBody(rectangleOfSize: bigWall.size)
bigWall.physicsBody?.dynamic = false
bigWall.physicsBody?.categoryBitMask = objectGroup
tallWall.physicsBody?.categoryBitMask = objectGroup
movingObjects.addChild(tallWall)
movingObjects.addChild(bigWall)
bigWall.position = CGPointMake(CGRectGetMaxX(self.frame) - bigWall.size.width / 2, CGRectGetMaxY(self.frame))
}
else
{
var bigWall = SKSpriteNode(imageNamed: "shortwall")
var tallWall = SKSpriteNode(imageNamed: "tallwall")
bigWall.position = CGPointMake(CGRectGetMaxX(self.frame) - bigWall.size.width / 2, CGRectGetMaxY(self.frame))
tallWall.position = CGPointMake(CGRectGetMaxX(self.frame) - tallWall.size.width / 2, CGRectGetMaxY(self.frame))
var moveObjects = SKAction.moveByX(0, y: -self.frame.size.height * 2, duration: NSTimeInterval(self.frame.size.height / 100))
var removeObjects = SKAction.removeFromParent()
var moveAndRemoveObjects = SKAction.sequence([moveObjects,removeObjects])
tallWall.physicsBody = SKPhysicsBody(rectangleOfSize: tallWall.size)
tallWall.physicsBody?.dynamic = false
bigWall.physicsBody = SKPhysicsBody(rectangleOfSize: bigWall.size)
bigWall.physicsBody?.dynamic = false
tallWall.runAction(moveAndRemoveObjects)
bigWall.runAction(moveAndRemoveObjects)
bigWall.physicsBody?.categoryBitMask = objectGroup
tallWall.physicsBody?.categoryBitMask = objectGroup
movingObjects.addChild(tallWall)
movingObjects.addChild(bigWall)
}
}
func rightAndMiddleObject(){
var rand = arc4random_uniform(2) + 1
if rand == 1
{
var bigWall = SKSpriteNode(imageNamed: "shortwall")
var tallWall = SKSpriteNode(imageNamed: "tallwall")
tallWall.position = CGPointMake(CGRectGetMaxX(self.frame) - tallWall.size.width / 2, CGRectGetMaxY(self.frame))
bigWall.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMaxY(self.frame))
var moveObjects = SKAction.moveByX(0, y: -self.frame.size.height * 2, duration: NSTimeInterval(self.frame.size.height / 100))
var removeObjects = SKAction.removeFromParent()
var moveAndRemoveObjects = SKAction.sequence([moveObjects,removeObjects])
tallWall.runAction(moveAndRemoveObjects)
bigWall.runAction(moveAndRemoveObjects)
tallWall.physicsBody = SKPhysicsBody(rectangleOfSize: tallWall.size)
tallWall.physicsBody?.dynamic = false
bigWall.physicsBody = SKPhysicsBody(rectangleOfSize: bigWall.size)
bigWall.physicsBody?.dynamic = false
bigWall.physicsBody?.categoryBitMask = objectGroup
tallWall.physicsBody?.categoryBitMask = objectGroup
movingObjects.addChild(tallWall)
movingObjects.addChild(bigWall)
}
else
{
var bigWall = SKSpriteNode(imageNamed: "shortwall")
var tallWall = SKSpriteNode(imageNamed: "tallwall")
bigWall.position = CGPointMake(CGRectGetMidX(self.frame) , CGRectGetMaxY(self.frame))
tallWall.position = CGPointMake(CGRectGetMaxX(self.frame) - tallWall.size.width / 2, CGRectGetMaxY(self.frame))
var moveObjects = SKAction.moveByX(0, y: -self.frame.size.height * 2, duration: NSTimeInterval(self.frame.size.height / 100))
var removeObjects = SKAction.removeFromParent()
var moveAndRemoveObjects = SKAction.sequence([moveObjects,removeObjects])
tallWall.runAction(moveAndRemoveObjects)
bigWall.runAction(moveAndRemoveObjects)
tallWall.physicsBody = SKPhysicsBody(rectangleOfSize: tallWall.size)
tallWall.physicsBody?.dynamic = false
bigWall.physicsBody = SKPhysicsBody(rectangleOfSize: bigWall.size)
bigWall.physicsBody?.dynamic = false
bigWall.physicsBody?.categoryBitMask = objectGroup
tallWall.physicsBody?.categoryBitMask = objectGroup
movingObjects.addChild(tallWall)
movingObjects.addChild(bigWall)
}
}
func LeftAndMiddleObject(){
var rand = arc4random_uniform(2) + 1
if rand == 1
{
var bigWall = SKSpriteNode(imageNamed: "shortwall")
var tallWall = SKSpriteNode(imageNamed: "tallwall")
tallWall.position = CGPointMake(CGRectGetMinX(self.frame) + tallWall.size.width / 2, CGRectGetMaxY(self.frame))
bigWall.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMaxY(self.frame))
var moveObjects = SKAction.moveByX(0, y: -self.frame.size.height * 2, duration: NSTimeInterval(self.frame.size.height / 100))
var removeObjects = SKAction.removeFromParent()
var moveAndRemoveObjects = SKAction.sequence([moveObjects,removeObjects])
tallWall.runAction(moveAndRemoveObjects)
bigWall.runAction(moveAndRemoveObjects)
tallWall.physicsBody = SKPhysicsBody(rectangleOfSize: tallWall.size)
tallWall.physicsBody?.dynamic = false
bigWall.physicsBody = SKPhysicsBody(rectangleOfSize: bigWall.size)
bigWall.physicsBody?.dynamic = false
bigWall.physicsBody?.categoryBitMask = objectGroup
tallWall.physicsBody?.categoryBitMask = objectGroup
movingObjects.addChild(tallWall)
movingObjects.addChild(bigWall)
}
else
{
var bigWall = SKSpriteNode(imageNamed: "shortwall")
var tallWall = SKSpriteNode(imageNamed: "tallwall")
bigWall.position = CGPointMake(CGRectGetMidX(self.frame) , CGRectGetMaxY(self.frame))
tallWall.position = CGPointMake(CGRectGetMinX(self.frame) + tallWall.size.width / 2, CGRectGetMaxY(self.frame))
var moveObjects = SKAction.moveByX(0, y: -self.frame.size.height * 2, duration: NSTimeInterval(self.frame.size.height / 100))
var removeObjects = SKAction.removeFromParent()
var moveAndRemoveObjects = SKAction.sequence([moveObjects,removeObjects])
tallWall.runAction(moveAndRemoveObjects)
bigWall.runAction(moveAndRemoveObjects)
tallWall.physicsBody = SKPhysicsBody(rectangleOfSize: tallWall.size)
tallWall.physicsBody?.dynamic = false
bigWall.physicsBody = SKPhysicsBody(rectangleOfSize: bigWall.size)
bigWall.physicsBody?.dynamic = false
bigWall.physicsBody?.categoryBitMask = objectGroup
tallWall.physicsBody?.categoryBitMask = objectGroup
movingObjects.addChild(tallWall)
movingObjects.addChild(bigWall)
}
}
func scoreIncrement(){
score = score + 1
scoreLabel.text = "\(score)"
}
func didBeginContact(contact: SKPhysicsContact) {
println("contact")
if contact.bodyA.categoryBitMask == gapGroup || contact.bodyB.categoryBitMask == gapGroup {
println("gap contact")
} else {
gameOver = 1
movingObjects.speed = 0
}
}
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
if gameOver == 0 {
ball.physicsBody?.velocity = CGVectorMake(0, 0)
ball.physicsBody?.applyImpulse(CGVectorMake(70,0))
}
}
override func update(currentTime: NSTimeInterval) {
}
}

Answer 1

The error suggests you are trying to add a child to a node while it already has a parent. The stack trace points you to leftObject method. In here you have an SKAction setup to move over a time interval and then remove from parent.
var moveObjects = SKAction.moveByX(0, y: -self.frame.size.height * 2, duration: NSTimeInterval(self.frame.size.height / 100))
var removeObjects = SKAction.removeFromParent()
var moveAndRemoveObjects = SKAction.sequence([moveObjects,removeObjects])
bigWall.runAction(moveAndRemoveObjects)
This adds the action to the node and it runs but your code path will continue down to
movingObjects.addChild(bigWall)
almost instantly. Looks like a race condition where you think the code will wait until the action has finished running before continuing on.

Answer 2

You have a instance property called bigWall and in most of your methods you create a local object called bigWall and add it to the scene. Since it is a new object each time the methods are call that works fine. However in the method leftObject you do not have a local object bigWall so it is referencing the instance property. The first time you call leftObject it will work fine adding your instance property bigWall to the scene. The second time you call the method it will try to add the bigWall instance property to the scene when it is already in the scene and that is where you will get the error.