Unity Facebook SDK v7.9.0 totally doesn't work on iOS (Unity version 5.3.2)

On Android everything is fine (no problems at all), but on iOS it doesn’t work at all, no callbacks (so I can’t even login)… Any advice?

Just found the solution and hidden cause of this problem. ( Read it up in this link : Log into Facebook)
I have Google Play Games integrated in my game too, and it has a GPGSAppController.mm which also overrides AppController, and have a openURL function insides it, and somehow when the openURL error which was supposed to happen at UnityAppController.mm’s openURL , didnt trigger inside GPGSAppController.mm’s openURL, causing the Facebook Login to just hang at the white screen after user’s permission interaction. Just put this 2 scripts (https://bitbucket.org/snippets/etliaojing/aanKj) in your build ( if you dont already have a script that overrides UnityAppController) and everything will be fine. In the case where you already have one , make sure to apply similar fix to the openURL function to your AppController script.