"How to fix not saved or loading data“

Question

因此，我正在为我的蛇游戏使用一个定制器，我正在使用PlayerPrefs来保存蛇的首选外观。现在，每次我测试运行游戏时，playerprefs中保存的字符串并没有加载，它只是空的。

我已经尝试过在Start()、Awake()和Update()方法上获取字符串数据，但它们都没有加载数据。另外，我在保存数据的每一行中都添加了PlayerPrefs.Save()。

这是我的代码，用于更新所有网格，使其与保存的字符串相同。我已经把它放到了Update方法中。

lesnek = GameObject.FindGameObjectsWithTag("LeWorm");

        objName = PlayerPrefs.GetString("meshName");

        if (PlayerPrefs.HasKey("meshName"))
        {
            if (objName == PlayerPrefs.GetString("meshName"))
            {
                leMesh = Resources.Load<GameObject>(@"Models\" + objName);
            }
            else
            {
                objName = PlayerPrefs.GetString("meshName");
                leMesh = Resources.Load<GameObject>(@"Models\" + objName);
            }
        }
        if (objName != null || objName != "")
        {
            objName = "Sphere";
            leMesh = Resources.Load<GameObject>(@"Models\" + objName);
        }

        foreach (GameObject change in lesnek)
        {
            if (objName != null || objName != "")
            {
                if (change.GetComponent<MeshFilter>() == null)
                {
                    change.AddComponent<MeshFilter>();
                    change.GetComponent<MeshFilter>().mesh = leMesh.GetComponent<MeshFilter>().sharedMesh;
                    PlayerPrefs.SetString("meshName", objName);
                    PlayerPrefs.Save();
                }
                else
                {
                    change.GetComponent<MeshFilter>().mesh = leMesh.GetComponent<MeshFilter>().sharedMesh;
                    PlayerPrefs.SetString("meshName", objName);
                    PlayerPrefs.Save();
                }
            }
        }

每次运行这段代码时，我都会收到一个错误，并且没有在playerpref中加载或保存字符串。

Answer 1

这里有一些问题，您的空引用错误是一个主要原因。

我将对您的代码进行注释，以显示您的错误所在，并提供替代解决方案。

// If possible it would be better to assign this object in the inspect rather then 
// using a GameObject.Find method, Also this is error prone due to the timing of 
// the call, for example if this is in a start this Object may not exist yet.
// Another solution would to be create an event and when you load the skin
// Have that event fire off that its been loaded and everything that needs
// to listen to it will get the change.
lesnek = GameObject.FindGameObjectsWithTag("LeWorm");

//  GetString has an alternative method where you can pass a default value
//  I would recommend using this method instead.
objName = PlayerPrefs.GetString("meshName");    // POINT A

// Honestly this check seems a tad bit redundant since you already
// attempted to load this preference.
// POINT B
if (PlayerPrefs.HasKey("meshName"))  // Since you have said this is empty playerPrefs is empty.
{
    // At this point it should equal this since you already set it to this in Point A
    if (objName == PlayerPrefs.GetString("meshName"))
    {
        leMesh = Resources.Load<GameObject>(@"Models\" + objName);
    }
    else
    {
        // This case should never get called, because of Point A and your if condition.
        objName = PlayerPrefs.GetString("meshName");
        leMesh = Resources.Load<GameObject>(@"Models\" + objName);
    }
}

if (objName != null || objName != "")  // This completely nullifies all the work in Point B
{
    objName = "Sphere";
    leMesh = Resources.Load<GameObject>(@"Models\" + objName);
}
foreach (GameObject change in lesnek)
{
    if (objName != null || objName != "")
    {
        if (change.GetComponent<MeshFilter>() == null)
        {
            change.AddComponent<MeshFilter>();
            change.GetComponent<MeshFilter>().mesh = leMesh.GetComponent<MeshFilter>().sharedMesh;
            PlayerPrefs.SetString("meshName", objName);
            PlayerPrefs.Save();
        }
        else
        {
            change.GetComponent<MeshFilter>().mesh = leMesh.GetComponent<MeshFilter>().sharedMesh;
            PlayerPrefs.SetString("meshName", objName);
            PlayerPrefs.Save();
        }
    }
}

无需详细介绍，假设这是一种初始化方法，而不是start，这就是我要做的更改

// This would be better as a class variable rather then a local variable
string meshName = PlayerPrefs.GetString("meshName", "Sphere");  
// Skipping point B because it is redundant
leMesh = Resources.Load<GameObject>(@"Models\" + meshName);  // Is this a GameObject or is it a Mesh???

MeshFilter leMeshFilter = leMesh.GetComponent<MeshFilter>();
if(leMeshFilter != null)
{
    foreach (GameObject change in lesnek)
    {
        MeshFilter meshFilter = change.GetComponent<MeshFilter>();
        if(meshFilter != null)
        {
            meshFilter.mesh = leMeshFilter.sharedMesh;
        }
        else
        {
            meshFilter = change.AddComponent<MeshFilter>();
            meshFilter.mesh = leMeshFilter.sharedMesh;
        }
    }
}

这个例子唯一不做的事情就是保存你的PlayerPreference。这是仅当您更改皮肤时才应该做的事情。因此，无论您在做什么，请保存首选项。

Answer 2

未找到游戏对象"leMesh“。第一步是确保它确实被找到了。因此，让我们确保了解它的状态，以便对其进行调试：

if (PlayerPrefs.HasKey("meshName"))
    {
        Debug.Log("PlayerPrefs does have the key we are looking for and it is " + PlayerPrefs.GetString("meshName"));

        /// This is redundant you just set objName to the string earlier
        /// objName = PlayerPrefs.GetString("meshName");
        if (objName == PlayerPrefs.GetString("meshName"))
        {
            leMesh = Resources.Load<GameObject>(@"Models\" + objName);
        }
        else
        {
            /// And here you do it again, constantly trying to get that string
            /// In order to find the object, of course if the string doesnt exist
            /// youll simply get an unassigned referenceException on this line:
            /// change.GetComponent<MeshFilter>().mesh = leMesh.GetComponent<MeshFilter>().sharedMesh
            objName = PlayerPrefs.GetString("meshName");
            leMesh = Resources.Load<GameObject>(@"Models\" + objName);
        }
    }

现在，如果你的控制台日志告诉你meshName返回了一个值，那么你访问的资源是错误的，在这种情况下，你试图从"Models“前面删除"@”。否则，就没有名为meshName的playerPrefs字符串。

ref