Hierarchy窗口扩展（给物体添加一个标识）

第一种

InitializeOnLoadMethod  //初始化加载方法

EditorApplication.hierarchyWindowItemOnGUI 当绘制层次窗口里面Item项时候

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEditor;


public class Script
{
  [InitializeOnLoadMethod]//初始化加载方法
  
   //EditorApplication.hierarchyWindowItemOnGUI 当绘制层次窗口里面Item项时候
    static void InitializeOnLoadMethod()
    {
        EditorApplication.hierarchyWindowItemOnGUI = delegate (int intstanceID, Rect selectionRect)
          {
              if(Selection.activeObject&&intstanceID==Selection.activeObject.GetInstanceID())
              {
                  float width = 50f;
                  float height = 20f;
                  selectionRect.x += (selectionRect.width - width);
                  selectionRect.width = width;
                  selectionRect.height = height;
                  //GUIStyle style = new GUIStyle();
                  //style.normal.textColor = Color.red;
                  //GUI.Label(selectionRect, "你好",style);
                  GUI.Label(selectionRect, AssetDatabase.LoadAssetAtPath<Texture>("Assets/unity.png"));
                 
              }
          };
    }
}

第二种

 InitializeOnLoad  //仅对类有作用  unity 会在用户之前去初始化这个编辑器类
 

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using UnityEditor;
// unity 会在用户之前去初始化这个编辑器类
[InitializeOnLoad]//仅对类有作用
public class NewBehaviourScript1 
{
   static NewBehaviourScript1()
    {
        EditorApplication.hierarchyWindowItemOnGUI += fun;
    }
    static void fun(int count,Rect selectionRect)
    {
        var a = EditorUtility.InstanceIDToObject(count) as GameObject;
        if(a!=null)
        {
            Rect rectCheck = new Rect(selectionRect);
            rectCheck.x = rectCheck.width;
            rectCheck.width = 30;
            rectCheck.height = 18;
            GUIStyle gUI = new GUIStyle();
            gUI.normal.textColor = Color.red;
            Object c=null;
            if (a.name.Contains("boss"))
            {
                 c = AssetDatabase.LoadAssetAtPath<Object>("Assets/9.png");
               
            }
            if(a.name.Contains("Canvas"))
            {
                c = AssetDatabase.LoadAssetAtPath<Object>("Assets/10.png");
            }
            if(c!=null)
            {
                var c1 = EditorGUIUtility.ObjectContent(c, typeof(Image)).image;
                GUI.Label(rectCheck, c1);
            }
            

        }

    }

}