c# - 无法解释的变量增加

Question

在我用来更改按钮设置的循环之一中，我还使用了 AddListener 函数，而不是 Inspector 中的函数。我有 5 个项目，给出了 0-4 的“i”范围，但是当我通过它应该调用的函数打印“i”时，无论我按什么按钮，它总是记录 5，这很奇怪，因为“i”从来没有达到 5。有什么想法吗？

附言我使用 CustomEditor 在检查器中显示 2 个按钮“预览布局”和“删除预览”。

代码:

using UnityEngine;
using System.Collections;
using UnityEditor;
using UnityEngine.UI;

public class RateMeManager : MonoBehaviour {

    public GameObject rateMeCanvas;
    public Sprite emptyStar, fullStar, button;
    public float spriteWidth, spriteHeight, spritePadding;

    [HideInInspector]
    public GameObject currentCanvas, tempButton;

    void Start () {
        RemovePreview();
        GenerateStars();
    }

    // Update is called once per frame
    public void GenerateStars () {
        RectTransform myRectTransform;
        if (currentCanvas != null)
        {
            GameObject temp;
            temp = currentCanvas;
            DestroyImmediate(temp);
        }
        currentCanvas = Instantiate(rateMeCanvas, Vector3.zero, Quaternion.identity) as GameObject;
        GameObject subCanvas = currentCanvas.transform.FindChild("subCanvas").gameObject;
        myRectTransform = subCanvas.GetComponent<RectTransform>();
        myRectTransform.sizeDelta = new Vector2((5*spriteWidth) + (4*spritePadding), spriteHeight);
        myRectTransform.anchoredPosition = Vector2.zero;
        Button[] buttons = subCanvas.GetComponentsInChildren<Button>();
        float[] positions = new float[] {((2*spriteWidth)+(2*spritePadding))*-1, ((1 * spriteWidth) + (1 * spritePadding)) * -1 , 0, ((1 * spriteWidth) + (1 * spritePadding)), ((2 * spriteWidth) + (2 * spritePadding))};
        for (int i = 0; i < buttons.Length; i++)
        {
            Debug.Log(i);
            tempButton = buttons[i].gameObject;
            tempButton.GetComponent<Button>().image.sprite = emptyStar;
            myRectTransform = buttons[i].GetComponent<RectTransform>();
            myRectTransform.sizeDelta = new Vector2(spriteWidth, spriteHeight);
            myRectTransform.anchoredPosition = new Vector2(positions[i], 0);
            tempButton.GetComponent<Button>().onClick.AddListener(() => OnGivenRate(i));
        }
    }

    public void RemovePreview()
    {
        DestroyImmediate(currentCanvas);
    }

    private void OnGivenRate(int stars)
    {
        Debug.Log("pressed star: " + stars);
    }

    public class RateMeEditor
    {
        [CustomEditor(typeof(RateMeManager))]
        public class button : Editor
        {
            public override void OnInspectorGUI()
            {
                base.OnInspectorGUI();

                RateMeManager myScript = (RateMeManager)target;
                if (GUILayout.Button("Preview Layout"))
                {
                    myScript.GenerateStars();
                }
                if (GUILayout.Button("Delete Preview"))
                {
                    myScript.RemovePreview();
                }
            }
        }
    }
}

Answer 1

你的错误在这里:

tempButton.GetComponent<Button>().onClick.AddListener(() => OnGivenRate(i));

在将它传递给 OnGivenRate 或使用闭包之前，您必须将 i 存储在一个变量中。因为在循环结束时 i 等于 5。这就是为什么当您单击按钮时 i 显示 5。

也一样:

var rate = i;
tempButton.GetComponent<Button>().onClick.AddListener(() => OnGivenRate(rate));

或

Action<int> OnGivenRateClosure(int rate)
{
    return () => OnGivenRate(rate);
}

与

tempButton.GetComponent<Button>().onClick.AddListener(OnGivenRateClosure(i));