SCNSceneSource identifiersOfEntries not working as expected in Playgrounds App

Question

I’m having no luck trying to selectively extract certain elements of a scene file. I’m using SCNSceneSource class. I’m running this swift code inside the Playgrounds App on my ipad pro. I’ve tried multiple dae, scn files using different ways. From the Resources directory.

I’ve also tried different class types, SCNScene, SCNNode, SCNGeometry, etc

Any help would be greatly appreciated.

guard let url = Bundle.main.url(forResource: "file", withExtension: "scn") else {
    fatalError("Failed to find model file")
}

let sceneSource = SCNSceneSource(url: url as URL, options: nil)!

//List identifiers
let identifiers = sceneSource.identifiersOfEntries(withClass: SCNGeometry.self) as [String]

for identifier in identifiers {
    print(identifiers)
}

Edit:

Btw, I’m using SketchUp to create the original Collada (DAE) files which I import into Xcode. SketchUp supports Collada 1.4 specification and schema. In a past SO answer, it was recommended to avoid Collada version 1.5 as its not supported by Scenekit.

When I review the Collada dae files in Xcode using scene graph (a hierarchy of nodes with attached geometries, lights, cameras etc. ) The attributes window corresponding to each node/geometry is showing “no identifier” when clicking on the different geometry/nodes in the scene graph. I was able to add some names by manually editing the xml schema in the dae file using a text editor (or clicking on the scene graph parts and renaming, on the relevant nodes/geometry... but even though each geometry element has an id=“geometry1” etc.... in the orignal Collada dae file schema.. that is still not showing up as the identifier in the attributes menu of Xcode.

Does anyone have a sample validated DAE file they can provide or link to, in others words, sceneSource.identifiersOfEntries(withClass: SCNGeometry.self) will return the SCNGeometry identifiers... this will help me troubleshoot any problems with SketchUp Collada dae files not being formatted properly by the SketchUp exporter.

Apple’s own scenekit documentation does not seemed to go into any details about how each scn class reconciles with the Collada schema.

NOTE: I’M not having a problem loading or using dae files in an iOS application. Or converting to an SCN file format. This problem only relates to extracting id’s from the sceneSource via “identfiersOfEntries”