iOS enumerateChildNodeswithName to access ALL physics bodies

Question

I'm writing a helper method to display a summary of all of the physics interactions (collisions and contacts) in an SpriteKit app on iOS.

I have a simple scene, with a boundary (from self.physicsBody = SKPhysicsBody(edgeLoopFromRect: frame)) and 3 simple shapes (2 squares and a circle) wich are added to the scene via addChild()

In my helper function, I want to search all nodes and if they have a physicsBody, print their category, collision and contactTest bit masks.

If I code the following:

enumerateChildNodesWithNeme("*") { node, _ in {
   print("Node: \(node.name)")
}

then I only get the 3 shapes listed:

Node: Optional("shape_blueSquare")
Node: Optional("shape_redCircle")
Node: Optional("shape_purpleSquare")

My scene's physicsBody is not returned. But if I use:

enumerateChildNodesWithNeme("..") { node, _ in {
   print("Node: \(node.name)")
}

then I get:

Node: Optional("shape_edge")

If I use:

enumerateChildNodesWithNeme("..//") { node, _ in {
   print("Node: \(node.name)")
}

I get nothing, whereas I thought this would move up the node tree to the scene and then recursively return all children. The search argument "//*" also returns just the 3 children.

All the time, the node count displayed by skView.showNodecount = true is 4.

So my question is: Is there a search argument for enumerateChildNodesWithName that will return all the nodes in a scene (including the scene itself) or have I misunderstood the relationship between the scene and it's children, in that a single search cannot search both? It may be the latter, as print("\(parent.children)") returns nil, when I was expecting to see self or some variation of such.

If this is the way that it works, and my code will find all physics bodies other that the scene's physics body, then that's fine - I can just handle that separately. I just want to make sure that I'm not potentially missing anything else. — Steve Ives
Printing something like print("\(parent.children)") will always end up with nil. I assume that here, implicit self is a GameScene or something like that. You are getting nil, because (according to the docs), the scene is a root node, so it can't have a parent. For example, you can't remove the scene from its parent (the self.parent property is always nil, when self is a current scene) thus something like self.removeFromParent() has no effect. — Whirlwind
You are welcome. Have you tried the code I've posted as an answer ? Does it work for you ? — Whirlwind

Whirlwind Whirlwind · Accepted Answer · 2016-04-06T12:47:27

This worked for me:

enumerateChildNodesWithName("//.") { (node, _) -> Void in
     print("Node: \(node.name)")
}

About // :

When placed at the start of the search string, this specifies that the search should begin at the root node and be performed recursively across the entire node tree.

About . :

Refers to the current node.

Also this might work for you as well (if you want to find all physics bodies within a given rectangle):

self.physicsWorld.enumerateBodiesInRect(frame) { (body, _) -> Void in
    print(body.node?.name)
}

iOS enumerateChildNodeswithName to access ALL physics bodies

1 Answers