Need help with Facebook SDK for Unity (iOS)!

Hello! I'm developing an indie game for Android and iOS. I'm using the Facebook SDK (https://developers.facebook.com/docs/unity/) for leaderboards and such. Everything is working fine on Android, but when I try to log-in with Facebook on iOS, it pops the Safari Facebook Log-In window and asks for permissions, when I accept the permissions Safari just stays open with a blank screen and it never goes back to my game. During this event I believe the Xcode debug log says this: http://imgur.com/acDi9zv . After building the iOS project from Unity, I just built the game for my iPhone without making any changes to anything in Xcode. What might be the problem? I guess I need to add some code in Xcode, but which files? The release of my game is getting delayed because of this problem. :/ Thank you in advance!

I'm using Unity 5.4.1f1, Facebook SDK 7.8 and Xcode 8.