FacebookLogin.cs

namespace Cloud
{
    public class FacebookLogin : MonoBehaviour
    {
        public void Login()
        {
            if (FB.IsLoggedIn)
            {
                FB.LogOut();
            }           
        }

        private void OnFacebookLoggedIn(ILoginResult result)
        {          
            if (result != null && string.IsNullOrEmpty(result.Error))
            {                              
                // check if linked to any existing accounts
                PlayFabClientAPI.GetPlayFabIDsFromFacebookIDs(new GetPlayFabIDsFromFacebookIDsRequest
                {
                    FacebookIDs = new List<string> {result.AccessToken.UserId},
                }, dsResult =>
                {                   
                    Debug.Log(dsResult.ToJson());
                    if (dsResult.Data.Count == 0)
                    {
                        Debug.Log("No attached facebook accounts");
                        LinkAccount(true, null);
                    }
                    else
                    {
                        if (_playfabIds[0].PlayFabId == PlayFabLogin.LoginResult.PlayFabId)
                        {    
                            Debug.Log("Already linked to this account!");
                        }
                        else
                        {
                            Debug.Log("Linked to a different playfab account!");
                            Debug.Log(_playfabIds[0].PlayFabId);
                        }
                    }
                }, error =>
                {                   
                    Debug.Log("failed to retrieve any attached playfab accounts " + error.GenerateErrorReport());
                });
            }
            else
            {
                Debug.LogError("Failed to login to facebook " + result.Error);
            }
        }

        public void Unlink()
        {            
            FB.LogOut();
            PlayFabClientAPI.UnlinkFacebookAccount(new UnlinkFacebookAccountRequest(), result =>
            {
                Debug.Log("Unlinked facebook account.");
                UpdateButtonStatus();
                
            }, error =>
            {
                Debug.LogError("Failed to unlink facebook account! " + error.GenerateErrorReport());
            });
        }      
                
        public void LinkAccount(bool forceLink, Action<bool> onComplete)
        {
            PlayFabClientAPI.LinkFacebookAccount(new LinkFacebookAccountRequest
            {
                AccessToken = AccessToken.CurrentAccessToken.TokenString,
                ForceLink = forceLink,
            }, accountResult =>
            {
                PlayFabLogin.LoginResult.InfoResultPayload.AccountInfo.FacebookInfo = new UserFacebookInfo
                {
                    FacebookId = AccessToken.CurrentAccessToken.UserId
                };
                Debug.Log("Linked account successfully");
                onComplete?.Invoke(true);
            }, error =>
            {
                Debug.Log("Failed to link facebook account! " + error.GenerateErrorReport());
                onComplete?.Invoke(false);
            });
        }
    }
}