Singleton Class

public class Singleton<T> : MonoBehaviour where T : MonoBehaviour
{
    private static T _instance;

    public static T Instance
    {
        get
        {
            if (_instance == null)
            {
                _instance = FindFirstObjectByType<T>();

                if (_instance == null)
                {
                    GameObject singletonObject = new GameObject(typeof(T).Name);
                    _instance = singletonObject.AddComponent<T>();
                }
            }

            return _instance;
        }
    }

    protected virtual void Awake()
    {
        if (_instance != null && _instance != this)
        {
            // If an instance already exists, destroy this new instance
            Destroy(gameObject);
            return;
        }

        // This is the first instance or the assigned instance, don't destroy it on scene load
        _instance = this as T;
        //DontDestroyOnLoad(gameObject);
    }
}