CoinArchivementObserver.cs

using System;
using UnityEngine;

/// <summary>
/// observer : đạt thành tựu thu thập đủ 10000 coin
/// </summary>
public class CoinArchivementObserver : MonoBehaviour
{
    private void Awake()
    {
        GameCenter.CurrencyChangedEvent += OnCurrencyChangedValue;
    }

    private void OnCurrencyChangedValue()
    {
        if (UserData.CurrentCoin == 10000)
        {
            // play âm thanh chúc mừng
            // pháo hoa các kiểu
            // hiện thông báo nhận thưởng ...
        }
    }

    private void OnDestroy()
    {
        GameCenter.CurrencyChangedEvent -= OnCoinChangedValue;
    }
}

CoinObserver.cs

using System;
using TMPro;
using UnityEngine;

public class CoinObserver : MonoBehaviour
{
    [SerializeField] private TextMeshProUGUI txtCoin;

    private void Awake()
    {
        GameCenter.CurrencyChangedEvent += OnCurrencyChangedValue;
    }

    private void OnCurrencyChangedValue()
    {
        txtCoin.text = $"{UserData.CurrentCoin}";
    }

    private void OnDestroy()
    {
        GameCenter.CurrencyChangedEvent -= OnCoinChangedValue;
    }
}

GameCenter.cs

using System;

public static class GameCenter
{
    // Action tương đương với việc sử dụng delegate void không tham số
    // public delegate void CurrencyChangedDelegate();
    // public static event CurrencyChangedDelegate CurrencyChangedEvent;

    public static event Action CurrencyChangedEvent;

    public static void OnCurrencyChangedEvent()
    {
        CurrencyChangedEvent?.Invoke();
    }
}

GameCenter2.cs

using System;

public static class GameCenter
{
    // Action tương đương với việc sử dụng delegate void không tham số
    // public delegate void CurrencyChangedDelegate();
    // public static event CurrencyChangedDelegate CurrencyChangedEvent;

    public static event Action CurrencyChangedEvent;

    public static void OnCurrencyChangedEvent()
    {
        CurrencyChangedEvent?.Invoke();
    }

    public static void Register(Action action)
    {
        CurrencyChangedEvent += action;
    }

    public static void UnRegister(Action action)
    {
        CurrencyChangedEvent -= action;
    }
}

GemObserver.cs

using System;
using TMPro;
using UnityEngine;

public class GemObserver : MonoBehaviour
{
    [SerializeField] private TextMeshProUGUI txtGem;

    private void Awake()
    {
        GameCenter.CurrencyChangedEvent += OnCurrencyChangedValue;
    }

    private void OnCurrencyChangedValue()
    {
        txtGem.text = $"{UserData.CurrentGem}";
    }

    private void OnDestroy()
    {
        GameCenter.CurrencyChangedEvent -= OnGemChangedValue;
    }
}

UserData.cs

public static class UserData
{
    private static long currentCoin;
    private static int currentGem;

    public static long CurrentCoin
    {
        get => currentCoin;
        set
        {
            currentCoin = value;
            GameCenter.CurrencyChangedInvoke();
        }
    }

    public static int CurrentGem
    {
        get => currentGem;
        set
        {
            currentGem = value;
            GameCenter.CurrencyChangedInvoke();
        }
    }
}