资源管理——对象池

游戏中，实例化是比较耗时的操作，在生成子弹、敌人等需要大量复制的对象时，如果都直接实例化，将增加许多没必要的内存和时间开销，因此我们应该针对这些对象使用对象池。

直接上对象池代码：

using UnityEngine;
using System.Collections.Generic;
using System.Collections;
 
public class ObjectPools : MonoBehaviour 
{
    private GameObject result;             //对象池要返回的当前对象
    private Dictionary<string, List<GameObject>> poolList;//对象池
    private string keyTag;                 //对象池字典Key
    private const float recycleTime = 5f;  //回收时间 
 
    #region Singleton
    private static ObjectPools defautPools;
    public static ObjectPools DefaultPools {
        get {
            return defautPools;
        }
    }
    #endregion
 
    void Awake()
    {
        poolList = new Dictionary<string, List<GameObject>>();
        defautPools = this;
    }
 
    /// <summary>
    /// 从对象池实例化
    /// </summary>
    public GameObject MyInstantiate(GameObject prefab, Vector3 position, Quaternion rotation)
    {
        keyTag = prefab.tag;
        //如有某个小集合的Key，并且小集合内元素数量大于0
        if(poolList.ContainsKey(keyTag) && poolList[keyTag].Count > 0)       //弹夹里面有子弹
        {
            result = (poolList[keyTag])[0];     //取弹夹里面的第一个子弹
            poolList[keyTag].Remove(result);        //从弹夹里面移除子弹
            result.transform.position = position;
            result.transform.rotation = rotation;
        }
        else
        {
            //如果元素不存在，添加元素
            if(!poolList.ContainsKey(keyTag))
            {
                poolList.Add(keyTag, new List<GameObject>());
            }
            result = (GameObject)Instantiate(prefab, position, rotation);
        }
        //开启回收协程方法
        StartCoroutine(AutoRecycle(result));
        result.SetActive(true);
        return result;
    }
 
    /// <summary>
    /// 协程方法回收
    /// </summary>
    private IEnumerator AutoRecycle(GameObject bullet)
    {
        yield return new WaitForSeconds(recycleTime);
        poolList[bullet.tag].Add(bullet);
        bullet.SetActive(false);
    }
}