关于unity 如何动态生成sprite，废话不多说。我们具体看代码。

using UnityEngine;
using System.Collections;
public class SkillCDTimeSprite: MonoBehaviour
    {
        public string[] _sprite_name = {
            "num_0", "num_1", "num_2", "num_3", "num_4", "num_5", "num_6", "num_7", "num_8", "num_9"
        };
        // 技能是否处於CD状态
        public bool _skill_is_cd;
        public float _cd_time;
        UISprite _cd_sprite;
        UIAtlas _altas;
        GameObject _skill_btn;
        // Use this for initialization
        void Start()
            {
                // cd时间初始化
                _cd_time = 3 f;
                // 找到对应的altas
                _altas = (UIAtlas) Resources.Load("Prefabs/MyTest", typeof(UIAtlas));
                // CD阴影效果sprite初始化
                _cd_sprite = GameObject.Find("UI Root/Camera/SkillButton/CDSprite").GetComponent < UISprite > ();
                // 按钮初始化
                _skill_btn = GameObject.Find("UI Root/Camera/SkillButton");
            }
            // Update is called once per frame
        void Update()
        {
            if(_skill_is_cd)
            {
                float time = _cd_time * _cd_sprite.fillAmount;
                time -= Time.deltaTime;
                // 更新cd和cd时间的sprite
                _skill_is_cd = UpdateCDSprite(_cd_time, time, _skill_btn, "CDSprite");
            }
        }
        void OnClick()
        {
            if(_skill_is_cd)
            {
                Debug.Log("技能CD");
            }
            else
            {
                Debug.Log("施放技能");
                _skill_is_cd = true;
                _cd_sprite.fillAmount = 1;
                // 在按钮下面创建sprite
                UISprite time_sprite = NGUITools.AddSprite(_skill_btn, _altas, _sprite_name[(int) _cd_time + 1]);
                time_sprite.height = 25;
                time_sprite.width = 18;
            }
        }
        bool UpdateCDSprite(float cd_time, float time_left, GameObject btn, string sprite_name)
            {
                // 获取btn按钮下cd的sprite
                UISprite cd_sprite = btn.transform.Find(sprite_name).GetComponent < UISprite > ();
                cd_sprite.fillAmount = time_left / cd_time;
                // 按钮下的cd时间sprite
                UISprite sprite = btn.transform.Find("Sprite").GetComponent < UISprite > ();
                // 处理剩余时间，显示对应的sprite
                if(time_left > 0)
                {
                    if((int) time_left < time_left) sprite.spriteName = _sprite_name[(int) time_left + 1];
                    else sprite.spriteName = _sprite_name[(int) time_left];
                    return true;
                }
                else｛ return false;｝｝｝