SceneKit and Wireframe on iOS

Does anyone know how to make a single object, SCNNodeMBS, render wireframe?
I need to be able to toggle some objects, but I can’t find an easy way to do this.

You may go with filling using lines:

sphereNode.geometry.firstMaterial.fillMode = SCNFillModeLines

I think that’s it.
I tried it by the SCNNode didn’t have a firstMaterial, but on retrospect that’s because it was a “container” for a bunch of children nodes. I can iterate those and try it.

Thank you.