Unity のプレハブをプールしておくコンテナ

InstancePool.cs

// BEGIN MIT LICENSE BLOCK //
//
// Copyright (c) 2016 dskjal
// This software is released under the MIT License.
// http://opensource.org/licenses/mit-license.php
//
// END MIT LICENSE BLOCK   //
/* 使い方
public GameObject Prefab;
private InstancePool enemyPool;
void Start(){
    enemyPool = new InstancePool(Prefab, 10000);
    for(var i = 0; i < 100; ++i){
        var e = enemyPool.GetInstance();
        // 取得したインスタンスを初期化
        // e.Value.Init()
    }
}
// アクティブインスタンスの列挙
for(var i = 0; i < enemyPool.Count; ++i){
    //enemyPool[i].Value.MyUpdate()
}
// 不要なインスタンスを返す
for(var i = 0; i < enemyPool.Count; ++i){
    if(!enemyPool[i].Value.activeInHierarchy){
        enemyPool.ReturnInstance(enemies[i]);
        --i;
        continue;
    }
}
*/
using UnityEngine;

public class InstancePool {

    public struct Node {
        public GameObject Value;
        public readonly int LocationInPool;
        public Node(GameObject value, int loc) {
            Value = value;
            LocationInPool = loc;
        }
    }
    private Node[] pool;

    private int count;
    public int Count { get { return count; } }
    public int Capacity { get { return pool.Length; } }
    public bool HasSurplus() { return Capacity - Count > 0; }

    public InstancePool(GameObject prefab, int capacity) {
        pool = new Node[capacity];
        for(var i = 0; i < capacity; ++i) {
            pool[i] = new Node(Object.Instantiate(prefab), i);
            pool[i].Value.SetActive(false);
        }
        count = 0;
    }

    public Node GetInstance() {
        Debug.Assert(Capacity > Count, "Run out of instance.");
        return pool[count++];
    }

    public void ReturnInstance(Node item) {
        Debug.Assert(count > 0, "Pool is empty.");
        Debug.Assert(!item.Value.activeInHierarchy, "Returned instance is active.");
        var inactive = pool[item.LocationInPool].Value;
        pool[item.LocationInPool].Value = pool[--count].Value;
        pool[count].Value = inactive;
    }

    public void ReturnInactives() {
        for(var i = 0; i < count; ++i) {
            if (!pool[i].Value.activeInHierarchy) {
                ReturnInstance(pool[i]);
                --i;
                continue;
            }
        }
    }

    public Node this[int i]
    {
        get
        {
            Debug.Assert(i < Count, "Index exceeds count.");
            return pool[i];
        }
    }
}