Required Attribute特性：用于任何对象属性，如果对应属性没有赋值，则在检查器中出现对应的提示消息。

直接添加特性

    [Required]
    public GameObject MyGameObject;

也可以自定义消息

    [Required("自定义错误消息.")]
    public Rigidbody MyRigidbody;

当然可以使用$关键字使用动态消息

    public string DynamicMessage = "Dynamic Message";
    [Required("$DynamicMessage")]
    public GameObject GameObject_DynamicMessage;

    [Required("$ReturnStringFunction")]
    public GameObject GameObject_DynamicMessage1;
    public string ReturnStringFunction()
    {
        return "菜鸟海澜";
    }

也可以显示不同的消息类型，但是None和Info不显示，目前不知道就是这么设定的还是BUG？、

    [Required("$DynamicMessage", InfoMessageType.None)]
    public GameObject GameObject_None;
    [Required("$DynamicMessage", InfoMessageType.Info)]
    public GameObject GameObject_Info;
    [Required("$DynamicMessage", InfoMessageType.Warning)]
    public GameObject GameObject_Warning;
    [Required("$DynamicMessage",InfoMessageType.Error)]
    public GameObject GameObject_Error;

完整示例代码

using Sirenix.OdinInspector;
using UnityEngine;

public class RequiredExample : MonoBehaviour
{

    [Required]
    public GameObject MyGameObject;

    [Required("自定义错误消息.")]
    public Rigidbody MyRigidbody;

    public string DynamicMessage = "Dynamic Message";
    [Required("$DynamicMessage")]
    public GameObject GameObject_DynamicMessage;

    [Required("$ReturnStringFunction")]
    public GameObject GameObject_DynamicMessage1;
    public string ReturnStringFunction()
    {
        return "菜鸟海澜";
    }

    [Required("$DynamicMessage", InfoMessageType.None)]
    public GameObject GameObject_None;
    [Required("$DynamicMessage", InfoMessageType.Info)]
    public GameObject GameObject_Info;
    [Required("$DynamicMessage", InfoMessageType.Warning)]
    public GameObject GameObject_Warning;
    [Required("$DynamicMessage",InfoMessageType.Error)]
    public GameObject GameObject_Error;
}

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更多教程内容详见：革命性Unity 编辑器扩展工具 — Odin Inspector 系列教程