NSInvalidArgumentException : A Node can't parent itself - swift

Question

I would like to know what it means when we get an error like the 'NSInvalidArgumentException', reason: 'A Node can't parent itself' :
2015-03-04 01:51:33.421 FlappyPOOSwift[1789:155918] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'A Node can't parent itself: <SKSpriteNode> name:'(null)' texture:[<SKTexture> 'pipeDown' (30 x 160)] position:{0, 851} size:{60, 320} rotation:0.00'
*** First throw call stack:
(
0 CoreFoundation 0x0000000105361f35 __exceptionPreprocess + 165
1 libobjc.A.dylib 0x000000010705bbb7 objc_exception_throw + 45
2 CoreFoundation 0x0000000105361e6d +[NSException raise:format:] + 205
3 SpriteKit 0x0000000105c23d14 -[SKNode(setParent) setParent:] + 134
4 SpriteKit 0x0000000105c1c1ea -[SKNode addChild:] + 179
5 FlappyPOOSwift 0x00000001051754d6 _TFC14FlappyPOOSwift9GameScene10spawnPipesfS0_FT_T_ + 2294
6 FlappyPOOSwift 0x0000000105176e28 _TFFC14FlappyPOOSwift9GameScene13didMoveToViewFS0_FCSo6SKViewT_U_FT_T_ + 56
7 FlappyPOOSwift 0x0000000105176e67 _TTRXFo__dT__XFdCb__dT__ + 39
8 SpriteKit 0x0000000105c11586 -[SKRunBlock updateWithTarget:forTime:] + 99
9 SpriteKit 0x0000000105beb586 _ZN11SKCSequence27cpp_updateWithTargetForTimeEP9SKCSprited + 92
10 SpriteKit 0x0000000105be374c _ZN9SKCRepeat27cpp_updateWithTargetForTimeEP9SKCSprited + 40
11 SpriteKit 0x0000000105c3bce8 _ZN9SKCSprite6updateEd + 170
12 SpriteKit 0x0000000105bf5435 -[SKScene _update:] + 120
13 SpriteKit 0x0000000105c0f949 -[SKView(Private) _update:] + 563
14 SpriteKit 0x0000000105c0d2d9 -[SKView renderCallback:shouldBlock:] + 837
15 SpriteKit 0x0000000105c0a391 __29-[SKView setUpRenderCallback]_block_invoke + 56
16 SpriteKit 0x0000000105c36df4 -[SKDisplayLink _callbackForNextFrame:] + 256
17 QuartzCore 0x0000000109c73747 _ZN2CA7Display15DisplayLinkItem8dispatchEv + 37
18 QuartzCore 0x0000000109c7360f _ZN2CA7Display11DisplayLink14dispatch_itemsEyyy + 315
19 CoreFoundation 0x00000001052c9f64 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 20
20 CoreFoundation 0x00000001052c9b25 __CFRunLoopDoTimer + 1045
21 CoreFoundation 0x000000010528ce5d __CFRunLoopRun + 1901
22 CoreFoundation 0x000000010528c486 CFRunLoopRunSpecific + 470
23 GraphicsServices 0x000000010c70e9f0 GSEventRunModal + 161
24 UIKit 0x0000000105da3420 UIApplicationMain + 1282
25 FlappyPOOSwift 0x000000010517a89e top_level_code + 78
26 FlappyPOOSwift 0x000000010517a8da main + 42
27 libdyld.dylib 0x0000000107847145 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)
Thanks in advance.
hi i guess ill just show you the code
func spawnPipes() {
let pipePair = SKNode()
pipePair.position = CGPointMake(self.frame.size.width + pipeUpTexture.size().width * 2, 0)
pipePair.zPosition = -10
let height = UInt32(self.frame.size.height / 4)
let y = arc4random() % height + height
let pipeDown = SKSpriteNode (texture: pipeDownTexture)
pipeDown.setScale(2.0)
pipeDown.position = CGPointMake(0.0 , CGFloat(y) + pipeDown.size.height + CGFloat(pipeGap))
pipeDown.physicsBody = SKPhysicsBody (rectangleOfSize: pipeDown.size)
pipeDown.physicsBody?.dynamic = false
pipeDown.addChild(pipeDown)
//pipe Up
**let pipeUp = SKSpriteNode (texture: pipeUpTexture)**
pipeUp.setScale(2.0)
pipeUp.position = CGPointMake(0.0 , CGFloat(y))
pipeUp.physicsBody = SKPhysicsBody (rectangleOfSize: pipeUp.size)
pipeUp.physicsBody?.dynamic = false
pipeUp.addChild(pipeUp)
pipePair.runAction(PipesMoveAndRemove)
self.addChild(pipePair)
}
I guess the lines which are ** marked have the error but i can't see them in the Xcode. I hope you understand what I'm trying to say

Answer 1

My guess is that either :
You are trying to add the node to itself (as the error mention), like for example : pipeDownNode.addChild(pipeDownNode) instead of anotherNode.addChild(pipeDownNode)
You are trying to add node at the same node twice, like : aNode.addChild(pipeDownNode) and pipeDownNode.parent = aNode
Let me know if it helped. Otherwise, please add some code (where you add the node).