Unity2D: Creating a Cross-Platform Multi-Player Game in Unity Error!

Hi, i'm following this tutorial on raywenderlich to do with multiplayer, since Unity updated, they have added a new method for the participant lefting the event. So I am getting this error on Unity:

Assets/Script/Multiplayer/GPG Multiplayer/MultiplayerController.cs(8,14): error CS0738: MultiplayerController' does not implement interface member > GooglePlayGames.BasicApi.Multiplayer.RealTimeMultiplayerListener.OnParticipantLeft(GooglePlayGames.BasicApi.Multiplayer.Participant)' and the best implementing candidate MultiplayerController.OnRoomSetupProgress(float)' return type void' does not match interface member return type `void'

Whilst following the tutorial, I saw that someone in the comment section had the same error as me and someone replied back, however I wasn't sure how I should implement it as he didn't really explain it in great and clear detail!I also do not know how to create my own OnParticipantLeft(Participant leavingPlayer) method, which is why I was following the tutorial!

Hmm... looks like since this tutorial was written, they've added a new method or two to that interface. Here's the new method they're expecting to see

/// /// Raises the participant left event. /// This is called during room setup if a player declines an invitation /// or leaves. The status of the participant can be inspected to determine /// the reason. If all players have left, the room is closed automatically. /// /// name="participant">Participant that left void > OnParticipantLeft(Participant participant); If you just want to get > your project going again, you can add your own > OnParticipantLeft(Participant leavingPlayer) method to your > MultiplayerController object and have it print out a debug message or > two. > > In an actual game, you could probably use this to make sure, say, your > lobby display doesn't get messed up if a player joins, then leaves > while you're waiting for a third or fourth player to join.

So anyway does anyone know how to fix this error? Below is my code:

    using UnityEngine;
    using UnityEngine.SceneManagement;
    using System.Collections;
    using GooglePlayGames;
    using GooglePlayGames.BasicApi.Multiplayer;
    using System.Collections.Generic;

  public class MultiplayerController : RealTimeMultiplayerListener 
   {
 public MPLobbyListener lobbyListener;
 private static MultiplayerController _instance = null;
 private uint minimumOpponents = 1;
 private uint maximumOpponents = 1;
 private uint gameVariation = 0;
 private byte _protocolVersion = 1;
 // Byte + Byte + 2 floats for position + 2 floats for velcocity + 1 float for rotZ
 private int _updateMessageLength = 22;
 private List<byte> _updateMessage;
 public MPUpdateListener updateListener;



 public string GetMyParticipantId() {
     return PlayGamesPlatform.Instance.RealTime.GetSelf().ParticipantId;
 }

 public List<Participant> GetAllPlayers() {
     return PlayGamesPlatform.Instance.RealTime.GetConnectedParticipants ();
 }

 private void StartMatchMaking() {
     PlayGamesPlatform.Instance.RealTime.CreateQuickGame (minimumOpponents, maximumOpponents, gameVariation, this);
 }

 private MultiplayerController() {
     _updateMessage = new List<byte>(_updateMessageLength);
 PlayGamesPlatform.DebugLogEnabled = true;
     PlayGamesPlatform.Activate ();
 }

 private void ShowMPStatus(string message) {
     Debug.Log(message);
     if (lobbyListener != null) {
         lobbyListener.SetLobbyStatusMessage(message);
     }
 }

 public void SendMyUpdate(float posX, float posY, Vector2 velocity, float rotZ) {
     _updateMessage.Clear ();
     _updateMessage.Add (_protocolVersion);
     _updateMessage.Add ((byte)'U');
     _updateMessage.AddRange (System.BitConverter.GetBytes (posX));  
     _updateMessage.AddRange (System.BitConverter.GetBytes (posY));  
     _updateMessage.AddRange (System.BitConverter.GetBytes (velocity.x));
     _updateMessage.AddRange (System.BitConverter.GetBytes (velocity.y));
     _updateMessage.AddRange (System.BitConverter.GetBytes (rotZ));
     byte[] messageToSend = _updateMessage.ToArray(); 
     Debug.Log ("Sending my update message  " + messageToSend + " to all players in the room");
     PlayGamesPlatform.Instance.RealTime.SendMessageToAll (false, messageToSend);
 }

 public void SignInAndStartMPGame() {
     if (! PlayGamesPlatform.Instance.localUser.authenticated) {
         PlayGamesPlatform.Instance.localUser.Authenticate((bool success) => {
             if (success) {
                 Debug.Log ("We're signed in! Welcome " + PlayGamesPlatform.Instance.localUser.userName);
                 StartMatchMaking();
             } else {
                 Debug.Log ("Oh... we're not signed in.");
             }
         });
     } else {
         Debug.Log ("You're already signed in.");
         StartMatchMaking();
     }
 }

 public void SignOut() {
     PlayGamesPlatform.Instance.SignOut ();
 }

 public bool IsAuthenticated() {
     return PlayGamesPlatform.Instance.localUser.authenticated;
 }

 public void TrySilentSignIn() {
     if (! PlayGamesPlatform.Instance.localUser.authenticated) {
         PlayGamesPlatform.Instance.Authenticate ((bool success) => {
             if (success) {
                 Debug.Log ("Silently signed in! Welcome " + PlayGamesPlatform.Instance.localUser.userName);
             } else {
                 Debug.Log ("Oh... we're not signed in.");
             }
         }, true);
     } else {
         Debug.Log("We're already signed in");
     }
 }

 public static MultiplayerController Instance {
     get {
         if (_instance == null) {
             _instance = new MultiplayerController();
         }
         return _instance;
     }
 }

 public void OnRoomSetupProgress (float percent)
 {
     ShowMPStatus ("We are " + percent + "% done with setup");
 }

 public void OnRoomConnected (bool success)
 {
     if (success) {
         ShowMPStatus ("We are connected to the room! I would probably start our game now.");
         lobbyListener.HideLobby();
         lobbyListener = null;
         SceneManager.LoadScene("MainGame");
     } else {
         ShowMPStatus ("Uh-oh. Encountered some error connecting to the room.");
     }
 }

 public void OnLeftRoom ()
 {
     ShowMPStatus ("We have left the room. We should probably perform some clean-up tasks.");
 }

 public void OnPeersConnected (string[] participantIds)
 {
     foreach (string participantID in participantIds) {
         ShowMPStatus ("Player " + participantID + " has joined.");
     }
 }

 public void OnPeersDisconnected (string[] participantIds)
 {
     foreach (string participantID in participantIds) {
         ShowMPStatus ("Player " + participantID + " has left.");
     }
 }

 public void OnRealTimeMessageReceived (bool isReliable, string senderId, byte[] data)
 {
     // We'll be doing more with this later...
     byte messageVersion = (byte)data[0];
     // Let's figure out what type of message this is.
     char messageType = (char)data[1];
     if (messageType == 'U' && data.Length == _updateMessageLength) { 
         float posX = System.BitConverter.ToSingle(data, 2);
         float posY = System.BitConverter.ToSingle(data, 6);
         float velX = System.BitConverter.ToSingle(data, 10);
         float velY = System.BitConverter.ToSingle(data, 14);
         float rotZ = System.BitConverter.ToSingle(data, 18);
         Debug.Log ("Player " + senderId + " is at (" + posX + ", " + posY + ") traveling (" + velX + ", " + velY + ") rotation " + rotZ);
         // We'd better tell our GameController about this.
         if (updateListener != null) {
             updateListener.UpdateReceived(senderId, posX, posY, velX, velY, rotZ);
         }
     }
 }

}

Thank you. :)