garden_client/Assets/AtlasUtility/Script/Editor/Postprocess.cs

namespace AtlasUtility
{
    using UnityEditor;
    using UnityEngine;

    using System.IO;
    using System.Collections.Generic;

    public class Postprocess : AssetPostprocessor
    {
        public static void OnPostprocessAllAssets(string[] importedAssets, string[] deletedAssets, string[] movedAssets, string[] movedFromAssetPaths)
        {
            List<string> pngPathList = new List<string>();

            for (int i = 0; i < deletedAssets.Length; i++)
            {
                if (Path.GetExtension(deletedAssets[i]) == ".png")
                {
                    pngPathList.Add(deletedAssets[i]);
                }
            }

            ReferenceManager.ResetReference(pngPathList);
        }
    }
}