Will I be able to work with Nikon raw files in Photos for IOS, or are the files not supported?

In Aperture,to use an external editor,you have to export a tiff, or similar to the App, and then bring that copy back into Aperture….Using Photos,when you talk about using another App “Plugin” to edit, does that mean there is no creating a copy and round-tripping? 

I don’t have this available yet, but am just trying to understand advantages/disadvantages of whats coming.

Thanks

david s