StateMachine.cs

using UnityEngine;
using System.Collections;

public class StateMachine<T> : MonoBehaviour
{
    private T _t;
    private T _stateToSet;
    public T state
    {
        get { return _t; }
        set
        {
            OnStateExit();
            _t = value;
            OnStateEnter();
        }
    }

    public void CueState(T state, float time)
    {
        CancelInvoke("InternalSetState");
        _stateToSet = state;
        Invoke("InternalSetState", time);
    }

    protected virtual void OnStateEnter()
    {
    }

    protected virtual void OnStateExit()
    {
    }

    private void InternalSetState()
    {
        state = _stateToSet;
    }
}