Trying to replaceChildNode with node in different .scn file, why isn't it working?

Question

I am trying to replace a node in my main .scn with another in a different .scn file. I've found the method which is

 func replaceChildNode(_ oldChild: SCNNode, 
                 with newChild: SCNNode)

but when I implement it. in my code, I get 1 warning and 2 errors:

warning= Expression implicitly coerced from 'SCNNode?' to 'Any'

error= 1.expected seperator (after with), 2.use of unresolved identifier 'with'.

even after error one fix 1 still get error 2 and the warning

I have defined my nodes the following way:

 var scene:SCNScene!
 var test3Scene:SCNScene!

in the loader it becomes:

 scene = SCNScene(named: "art.scnassets/x1.scn")
 test3Scene=SCNScene(named: "art.scnassets/test3.scn")

and the concerned function looks like this:

   @objc func buttonClicked(){
      print("clicked")
      sceneView.allowsCameraControl  = false
      if(selection=="avatar"){
        scene.rootNode.replaceChildNode(_, oldChild: scene.rootNode.childNode(withName: "test1 reference", recursively: true),
                                        with  newChild: test3Scene.rootNode.childNodes[0])
}


//scene.rootNode.childNode(withName: "test1 reference", recursively: true) being the oldChild
//test3Scene.rootNode.childNodes[0] being the new one

Can anyone help on making this work? Thanks for your time

Answer 1

The childNode(withName:recursively:) method returns an optional (SCNNode?) but replaceChildNode(_:with:) expects an SCNNode.

You need to unwrap the optional before using it in the call.

---

Additionally there are issues where both the argument labels and parameter names are used at the call site. This isn't valid. See Function Argument Labels and Parameter Names.

scene.rootNode.replaceChildNode(_, oldChild: A
                                with newChild: B)

should be

scene.rootNode.replaceChildNode(A,
                                with: B)