I'm unsure how to do it with iPhoto. My guess is it syncs up to Apple cloud, from which the NAS should be able to sync? At least once it's off the phone you don't have the sandbox, which is a bit stronger on Apple devices, IIRC.

My cameras are all Androids, so I use FolderSync to put things in the cloud. It being Android there's still a filesystem that it can scan. I use an app on my QNAP to bring them back home.