If you are having trouble connecting Facebook to your account, double check that you've enabled permissions under your phone's settings.

The error message is either:
"You have returned to the app without completing the log-in." or
"ENGINE_LOGIN_ERROR_PERMISSIONS"

To fix it:
Go to iPhone Settings > Facebook

Under the panel "allow these apps to use your account", make sure the tab next to Family Guy is set to on.

If it is already on, please turn it off and on again to re-trigger the permissions,

Then try logging in once more using Facebook.