试图从另一个类/对象引用一个公共属性，它总是空的

Question

我有一个 C# 脚本附加到一个名为 GameManager 的空对象。剧本是GameManager.cs。这是前几行：

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

public class GameManager : MonoBehaviour {
    public GameObject tilePrefab;
    public GameObject startTile;
    public GameObject lastTile;

我在相机上附加了另一个脚本，称为 CameraManager.cs。我试图从 lastTile 引用 GameManager 但它始终为空。这是 CameraManager.cs:

的完整代码

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

public class CameraManager : MonoBehaviour
{
    // Start is called before the first frame update
    private Vector3 currPos;
    private Vector3 newPos;
    public float CamMoveSpeed = 5f;
    GameManager gameManager;

    private void Awake() {
        gameManager = gameObject.AddComponent<GameManager>();
    }
    private void Start() {
    }

    private void Update() {
        if (gameManager.lastTile != null) {
            currPos = gameObject.transform.position;
            Vector3 tilePos = gameManager.lastTile.transform.position;
            newPos = new Vector3(currPos.x + tilePos.x, currPos.y + tilePos.y, currPos.z + tilePos.z);
            this.transform.position = Vector3.Lerp(currPos, newPos, CamMoveSpeed * Time.deltaTime);
            Debug.Log("Moving Camera...");
        } else {
            Debug.LogWarning("gameManager.lastTile is NULL");
        }
    }
}

This latest iteration is based on this SO question.之前的迭代是基于this SO question.

从另一个脚本/类引用值的正确方法是什么？

Answer 1

public class GameManager : MonoBehaviour {
    public GameObject tilePrefab;
    public GameObject startTile;
    public GameObject lastTile;
}

看起来您从未将这些变量分配给任何东西，因此它们将始终为空。

为了使它们不为空，您需要将它们分配给某些东西，例如

public class GameManager : MonoBehaviour {
    public GameObject tilePrefab = new GameObject("Name");
    public GameObject startTile = new GameObject("Name");
    public GameObject lastTile = new GameObject("Name");
}

或者你可以通过做动态设置它们

private void Update() {
    gameManager.lastTile = new GameObject("Name");
}