解决的问题使用grid放置item的时候，每次数据可能都不一样，但是每次都删除grid下面的节点，之后动态创建新的item是比较浪费的。

写个简单的工具函数，原理很简单。

1、先获得grid下面的可用item

2、根据data的大小进行初始化

3、每次在可用的item列表里面获取新的item，如果不够用了，就创建新的item

4、disable掉没用的item

附：每个grid下面预先要有一个名字包含“Template_”的模板item。这个模板不会被用，之前尝试过把这个模板也当做一个item正常使用，但是有些NGUI的widget会出现BUG。

using UnityEngine;
using System.Collections.Generic;
//qq group :333417608
public class UITools
{
    
    /* usage:
        List<GameObject> canUseList = UITools.GetCanUseItemList(gridRoot);
        for (int i=0; i<totalData.Length; ++i)
        {
            GameObject go = UITools.GetNewItemObj(canUseList, gridRoot, prefab);
            // do init
        }
        UITools.UnActiveUnuseItem(canUseList);
 
        // prefab is the template
     */
 
    static public GameObject GetNewItemObj (List<GameObject> canUseList, GameObject root, GameObject prefab)
    {
        GameObject go = null;
        if (canUseList.Count > 0) {
            go = canUseList [0];
            canUseList.RemoveAt (0);
        } else {
            go = NGUITools.AddChild (root, prefab);
        }
        NGUITools.SetActiveSelf (go, true);
        return go;
    }
    
    static public T GetNewItemObj<T> (List<T> canUseList, GameObject root, GameObject prefab) where T : Component
    {
        T item = null;
        if (canUseList.Count > 0) {
            item = canUseList [0];
            canUseList.RemoveAt (0);
        } else {
            item = NGUITools.AddChild (root, prefab).GetComponent<T>();
        }
        item.name = string.Format("{0:D3}", 0);
        NGUITools.SetActiveSelf (item.gameObject, true);
        return item;
    }
    
    static public List<GameObject> GetCanUseItemList (GameObject root)
    {
        List<GameObject> itemList = new List<GameObject> ();
        Transform rootT = root.transform;
        for (int i=0; i<rootT.childCount; ++i) {
            GameObject go = rootT.GetChild (i).gameObject;
            if (IsNotTemplateGameObject(go))
            {
                itemList.Add (go);
            }
        }
        return itemList;
    }
    
    static public List<T> GetCanUseItemList<T> (GameObject root) where T : Component
    {
        List<T> childrenList = new List<T> ();
        Transform rootT = root.transform;
        for (int i=0; i<rootT.childCount; ++i) {
            Transform child = rootT.GetChild (i);
            T t = child.GetComponent<T> ();
            if (t != null && IsNotTemplateGameObject(child.gameObject)) {
                childrenList.Add (t);
            }
        }
        return childrenList;
    }
    
    static public void UnActiveUnuseItem (List<GameObject> canUseList)
    {
        foreach (var item in canUseList) {
            NGUITools.SetActiveSelf (item, false);
        }
    }
    
    static public void UnActiveUnuseItem<T> (List<T> canUseList) where T : Component
    {
        foreach (var item in canUseList) {
            NGUITools.SetActiveSelf (item.gameObject, false);
        }
    }
    
    static private bool IsNotTemplateGameObject(GameObject go)
    {
        bool result = !go.name.ToLower().Contains("template_");
        if (!result && go.activeSelf)
        {
            NGUITools.SetActiveSelf(go, false);
        }
        return result;
    }
}