I'm trying to program an application for learning vocabulary words. I'd like to be able to easily add single words from the Books application using the "Share ..." affordance. However the share extension (and action extension) don't show up in that surface, even with TRUEPREDICATE as the NSExtensionActivationRule. Facebook shows up as a valid target though, so it seems like there's some way to do it. Is Facebook manually approved by Apple/is there any way that I can make this, even if it's not approvable by the App Store?