SpriteButton (Unity)

SpriteButton.cs

using UnityEngine;
using System.Collections;

public class SpriteButton : MonoBehaviour
{
  public Sprite buttonDownSprite = null;
  public GameObject targetObject = null;
  public string messageName = "";

  private Sprite normalSprite;
  private SpriteRenderer ren;
  private AudioManager am;

  // Use this for initialization
  void Start() {
    GameObject go = GameObject.FindGameObjectWithTag("AudioManager");
    if (go == null) {
      go = GameObject.Instantiate(Resources.Load("Prefab/AudioManager", typeof(GameObject))) as GameObject;
    }
    am = go.GetComponent<AudioManager>();

    ren = GetComponent<SpriteRenderer>();
    normalSprite = ren.sprite;

    if (collider2D == null) {
      gameObject.AddComponent<BoxCollider2D>();
    }
  }

  void OnMouseDown() {
    if (buttonDownSprite) {
      ren.sprite = buttonDownSprite;
    }
    am.PlayButton ();
  }

  void OnMouseUp() {
    ren.sprite = normalSprite;

    if (targetObject) {
      targetObject.SendMessage(messageName);
    }
  }

}