I'm trying to use Facebook login with an iOS app built in Unity. I'm using the Facebook Unity SDK (7.9.0). The login seems to work fine, but afterwards, instead of returning to the app, I stay in the safari window, with a blank white screen.
I saw some similar questions on StackOverflow, but none were answered in enough detail for me to work out what to do to fix it, and I don't have enough reputation to ask clarifying questions :-(
So I never found out what caused this problem, but I uninstalled the Facebook SDK and then reinstalled it and it works as expected now. I suspect that I didn't copy the code across from their examples exactly correct or something.