由于插值是 l=a*t+b(1-t)，因此使用下面的这段代码

spriteRenderer.color = Color.Lerp (color01, color02, lerV); 

只要使得lerV（即t）在0到1之间来回变换，即可使得颜色在两个颜色之间来回变换

public class Coin : MonoBehaviour {

public Color color01;
public Color color02;
public float smooth=1;
SpriteRenderer spriteRenderer;

// Use this for initialization
void Start () {
spriteRenderer = GetComponent<SpriteRenderer> ();
GameObject obj = GameObject.FindWithTag ("SceneInfoLoader");
if (obj)
playScene = obj.GetComponent<PlayScene> ();
}

// Update is called once per frame
void Update () {
float lerV=Mathf.PingPong(Time.time * smooth, 1);

spriteRenderer.color = Color.Lerp (color01, color02, lerV); 
}

}