CustomEditor的文件要放在Assets/Editor目录下

using UnityEditor;

using UnityEngine;

[CustomEditor(typeof(test))]

public class testEditor : Editor

{

    void OnEnable()

    {

    }

    public override void OnInspectorGUI()

    {

        test myTarget = (test)target;

        myTarget.MyValue = EditorGUILayout.IntSlider(

                "Val-you", myTarget.MyValue, , );

    }

}

照网上写的代码，报错，后来发现这个文件要放到Assets/Editor目录下
Instance of testEditor couldn't be created. The script class needs to derive from ScriptableObject and be placed in the Assets/Editor folder.