Adding two sprite nodes to parent node causes app to crash

Question

I've a simple sprite-kit game where I run an action (move one step) on a parent node:

SKSpriteNode *firstNode = [SKSpriteNode spriteNodeWithColor:[SKColor blackColor] size:CGSizeMake(100, 100)];
firstNode.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:firstNode.size];
firstNode.physicsBody.dynamic = YES;
firstNode.position = CGPointMake(100, 100);
[self addChild:firstNode];

SKSpriteNode *secondNode = [SKSpriteNode spriteNodeWithColor:[SKColor blackColor] size:CGSizeMake(100, 100)];
secondNode.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:secondBlock.size];
secondNode.physicsBody.dynamic = YES;
secondNode.position = CGPointMake(200, 200);
[self addChild:secondNode];

SKSpriteNode *parentNode = [SKSpriteNode node];

[parentNode addChild:firstNode];
[parentNode addChild:secondNode];

SKAction *moveOneStep = [SKAction moveBy:CGVectorMake(100,  0) duration:.1];

[parentNode runAction:moveOneStep];

but adding the firstNode as a child to parentNode causes app crash !!

Could anyone please tell me what is wrong with my code ?

Thanks,

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LearnCocos2D LearnCocos2D · Accepted Answer · 2014-08-02T10:49:42

Read the error messages in the Xcode Console. It will say something along the lines of "tried to add node with existing parent".

Breaking it down to the relevant code, you're doing this, which is illegal:

[self addChild:firstNode];
[self addChild:secondNode];

[parentNode addChild:firstNode];
[parentNode addChild:secondNode];

A node can't be the child of two parents. You have to decide whether they should be children of self or parentNode.

Adding two sprite nodes to parent node causes app to crash

1 Answers