You can still create .scnp in new Xcode releases: File menu - New - File... (cmd+n);
Select "SceneKit Scene File"; hit Next;
change the file name (Save As filed) from "SceneKit Scene.scn" to "SceneKit Scene.scnp"; hit Create.
You now have a 3d particles .scnp file which you can adjust in the editor (and finish the RayWenderlich Geometry Fighter project without any issues or workarounds).
hukdenis
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