Facebook not logging in on iOS

I integrated the FB SDK into my game but I can't actually sign in. This is what I'm doing:

1. I click the login button in my game
2. Safari opens
3. I sign in with a test user
4. I get a notification in safari saying "You have already authorized gamename"
5. I go back to my game and I'm not logged in.

Checking my debug logs in Xcode I'm getting the following error:


Facebook not logging in on iOS