如何在 Unity 中的场景之间传递数据（和引用）

A:

How can I pass score value from one scene to another?
如何将分数值从一个场景传递到另一个场景？

I’ve tried the following:
我尝试过以下方法：

Scene one:  场景一：

void Start () {
    score = 0;
    updateScoreView ();
    StartCoroutine (DelayLoadlevel(20));
}

public void updateScoreView(){
    score_text.text = "The Score: "+ score;
}

public void AddNewScore(int NewscoreValue){
    score = score + NewscoreValue;
    updateScoreView ();
}

IEnumerator DelayLoadlevel(float seconds){        
    yield return new WaitForSeconds(10);
    secondsLeft = seconds;
    loadingStart = true;
    do {        
        yield return new WaitForSeconds(1);
    } while(--secondsLeft >0);

    // here I should store my last score before move to level two
    PlayerPrefs.SetInt ("player_score", score);
    Application.LoadLevel (2);
}

Scene two:  场景二：

public Text score_text;
private int old_score;

// Use this for initialization
void Start () {    
    old_score = PlayerPrefs.GetInt ("player_score");
    score_text.text = "new score" + old_score.ToString ();      
}

but nothing displayed on screen, and there’s no error.
但屏幕上没有显示任何内容，也没有错误。

Is this the correct way to pass data ?
这是传递数据的正确方法吗？

I am using Unity 5 free edition, develop game for Gear VR (meaning the game will run in android devices).
我正在使用 Unity 5 免费版，为 Gear VR 开发游戏（意味着游戏将在 Android 设备上运行）。

Any suggestion?   有什么建议吗？

Q:

There are many ways to do this but the solution to this depends on the type of data you want to pass between scenes. Components/Scripts and GameObjects are destroyed when new scene is loaded and even when marked as static.
有很多方法可以做到这一点，但解决方案取决于您想要在场景之间传递的数据类型。当加载新场景时，甚至标记为static时，组件/脚本和游戏对象都会被销毁。

In this answer you can find
在这个答案中你可以找到

1. Use the static keyword
   使用static关键字

---

1. Use the static keyword.
1.使用static关键字。

Use this method if the variable to pass to the next scene is not a component, does not inherit from MonoBehaviour and is not a GameObject then make the variable to be static.
如果要传递到下一个场景的变量不是组件、不是从MonoBehaviour继承并且不是 GameObject，请使用此方法，然后将该变量设置为static 。

Built-in primitive data types such as int, bool, string, float, double. All those variables can be made a static variable.
内置原始数据类型，例如int 、 bool 、 string 、 float 、 double 。所有这些变量都可以成为static变量。

Example of built-in primitive data types that can be marked as static:
可以标记为 static 的内置原始数据类型的示例：

static int counter = 0;
static bool enableAudio = 0;
static float timer = 100;

These should work without problems.
这些应该可以正常工作。

---

Example of Objects that can be marked as static:
可以标记为 static 的对象示例：

public class MyTestScriptNoMonoBehaviour
{

}

then  然后

static MyTestScriptNoMonoBehaviour testScriptNoMono;

void Start()
{
    testScriptNoMono = new MyTestScriptNoMonoBehaviour();
}

Notice that the class does not inherit from MonoBehaviour. This should work.
请注意，该类不是从MonoBehaviour继承的。这应该有效。

---

Example of Objects that cannot be marked as static:
不能标记为 static 的对象示例：

Anything that inherits from Object, Component or GameObject will not work.
任何继承自Object 、 Component或GameObject的东西都不起作用。

1A.Anything that inherits from MonoBehaviour
1A .任何继承自MonoBehaviour的东西

public class MyTestScript : MonoBehaviour 
{

}

then  然后

static MyTestScript testScript;

void Start()
{
    testScript = gameObject.AddComponent<MyTestScript>();
} 

This will not work because it inherits from MonoBehaviour.
这不起作用，因为它继承自MonoBehaviour 。

1B.All GameObject:
1B . GameObject ：

static GameObject obj;

void Start()
{
    obj = new GameObject("My Object");
}  

This will not work either because it is a GameObject and GameObject inherit from an Object.
这也不起作用，因为它是GameObject并且GameObject继承自Object 。

Unity will always destroy its Object even if they are declared with the static keyword.
Unity 将始终销毁其Object即使它们是使用static关键字声明的。

See #2 for a workaround.
请参阅#2了解解决方法。

---

2.Use the DontDestroyOnLoad function.
2.使用DontDestroyOnLoad函数。

You only need to use this if the data to keep or pass to the next scene inherits from Object, Component or is a GameObject. This solves the problem described in 1A and 1B.
仅当要保留或传递到下一个场景的数据继承自Object 、 Component或者是GameObject时，才需要使用此选项。这解决了图1A和图1B中描述的问题。

You can use it to make this GameObject not to destroy when scene unloads:
您可以使用它来使该游戏对象在场景卸载时不被破坏：

void Awake() 
{
    DontDestroyOnLoad(transform.gameObject);
}

---

You can even use it with the static keyword solve problem from 1A and 1B:
您甚至可以将它与static关键字一起使用来解决1A和1B中的问题：

public class MyTestScript : MonoBehaviour 
{

}

then  然后

static MyTestScript testScript;

void Awake() 
{
    DontDestroyOnLoad(transform.gameObject);
}

void Start()
{
    testScript = gameObject.AddComponent<MyTestScript>();
} 

The testScript variable will now be preserved when new scene loads.
现在，当新场景加载时，将保留testScript变量。

3.Save to local storage then load during next scene.
3.保存到本地存储，然后在下一个场景中加载。

This method should be used when this is a game data that must be preserved when the game is closed and reopened. Example of this is the player high-score, the game settings such as music volume, objects locations, joystick profile data and so on.
当这是关闭并重新打开游戏时必须保留的游戏数据时，应使用此方法。例如，玩家的高分、游戏设置（例如音乐音量、物体位置、操纵杆配置文件数据等）。

Thare are two ways to save this:
有两种方法可以保存它：

3A.Use the PlayerPrefs API.
3A . PlayerPrefs API。

Use if you have just few variables to save. Let’s say player score:
如果您只有很少的变量需要保存，请使用。假设玩家得分：

int playerScore = 80;

And we want to save playerScore:
我们想要保存playerScore：

Save the score in the OnDisable function
将分数保存在OnDisable函数中

void OnDisable()
{
    PlayerPrefs.SetInt("score", playerScore);
}

Load it in the OnEnable function
在OnEnable函数中加载它

void OnEnable()
{
    playerScore  =  PlayerPrefs.GetInt("score");
}

3B.Serialize the data to json, xml or binaray form then save using one of the C# file API such as File.WriteAllBytes and File.ReadAllBytes to save and load files.
3B .将数据序列化为 json、xml 或 binaray 形式，然后使用 C# 文件 API 之一（例如File.WriteAllBytes和File.ReadAllBytes保存和加载文件。

Use this method if there are many variables to save.
如果要保存的变量很多，请使用此方法。

General, you need to create a class that does not inherit from MonoBehaviour. This class you should use to hold your game data so that in can be easily serialized or de-serialized.
一般来说，您需要创建一个不继承自MonoBehaviour的类。您应该使用此类来保存游戏数据，以便可以轻松地序列化或反序列化。

Example of data to save:
要保存的数据示例：

[Serializable]
public class PlayerInfo
{
    public List<int> ID = new List<int>();
    public List<int> Amounts = new List<int>();
    public int life = 0;
    public float highScore = 0;
}

Grab the DataSaver class which is a wrapper over File.WriteAllBytes and File.ReadAllBytes that makes saving data easier from this post.
从这篇文章中获取DataSaver类，它是File.WriteAllBytes和File.ReadAllBytes的包装器，可以更轻松地保存数据。

Create new instance:  创建新实例：

PlayerInfo saveData = new PlayerInfo();
saveData.life = 99;
saveData.highScore = 40;

Save data from PlayerInfo to a file named “players”:
将 PlayerInfo 中的数据保存到名为“players”的文件中：

DataSaver.saveData(saveData, "players");

Load data from a file named “players”:
从名为“players”的文件加载数据：

PlayerInfo loadedData = DataSaver.loadData<PlayerInfo>("players");