属性 UnityEngine.RequireComponent 在此声明类型上无效。 它仅对类声明有效

Question

I am trying to code my first game 'Tappy Bird' using Unity2D. When I try to run the app, I am receiving the following error message in Unity:

Assets/scripts/TapController.cs(6,6): error CS0592: The attribute UnityEngine.RequireComponent is not valid on this declaration type. It is valid on class declarations only

Code:

using System.Collections;

using System.Collections.Generic;

using UnityEngine;


public class NewBehaviourScript : MonoBehaviour

{
    [RequireComponent(typeof(Rigidbody2D))]

    public float tapForce = 10;

    public float tiltSmooth = 5;
    public Vector3 startPos;
    Rigidbody2D rigidbody;
    Quaternion downRotation;
    Quaternion forwardRotation;

    void Start()
    {
        rigidbody = GetComponent<Rigidbody2D();
        downRotation = Quaternion.Euler(0, 0, -90);
        forwardRotation = Quaternion.Euler(0, 0, 35);
    }

    void update()
    {
        if (input.GetMouseButtonDown(0))
        {
            transform.rotation = forwardRotation;
            rigidbody.AddForce(vector2.up * tapForce, ForceMode2D.Force);
        }
        transform.rotation = Quaternion.Lerp(
            transform.rotation, downRotation, tiltSmooth * Time.deltaTime);
    }

    void onTriggerEnter2D(Collider2D col){
        if(col.gameObject.tag == "ScoreZone") {
            //register a Score event
            //play sound
        }
        if(col.gmeObject.tag == "DeadZone") {
            //register a dead event
            //play a sound
        }
    }
}

Answer 1

If I understand your code right you should add attribute before class declaration:

[RequireComponent(typeof(Rigidbody2D))]
public class NewBehaviourScript : MonoBehaviour
{
...
}

Answer 2

The RequireComponent attribute that adds required components as dependencies needs to be set outside of your class.

https://docs.unity3d.com/ScriptReference/RequireComponent.html

Answer 3

https://docs.unity3d.com/ScriptReference/RequireComponent.html

Firstly, it should be in front of the class name;

Secondly, if you have attach the script to gameobject, you need to reattach again.

[RequireComponent(typeof(Rigidbody2D))]
public class NewBehaviourScript : MonoBehaviour
{
    //...
}