[置顶] 【Unity3D游戏开发】`UnityEditor' could not be found Are you missing a using directive ... (二九)

`UnityEditor' could not be found Are you missing a using directive or an assembly reference? 

using UnityEditor; 之后无法Building，会出错 .

using UnityEditor;   之后无法Build，出错，不导出时在编辑器里是没有报错的，运行也正常，导出时，却提示

error CS0246: The type or namespace name `UnityEditor' could not be found. Are you missing a using directive or an assembly reference?

解答：Note: This is an editor class. To use it you have to place your script in Assets/Editor inside your project folder. Editor classes are in the UnityEditor namespace so for C# scripts you need to add "using UnityEditor;" at the beginning of the script.
注意：这是一个编辑器类，如果想使用它你需要把它放到工程目录下的Assets/Editor文件夹下。编辑器类在UnityEditor命名空间下。所以当使用C#脚本时，你需要在脚本前面加上 "using UnityEditor"引用。