How to call a function from a script in another scene

In scene 1.

Create empty GameObject and name it "Script". Attached a script (eg: class name "Scene1.cs") that want to be calls from other scenes. Apply DontDestroyOnLoad on it.

 void Awake()
 {
   DontDestroyOnLoad(this);
 }

 public void TestCall()
 {
 // test
 }

In scene 2.

 private Scene1 scene1;
     // Use this for initialization
     void Start () 
     {
         scene1 = GameObject.Find("Script").GetComponent<Scene1>();
         scene1.TestCall();
     }

There are several ways to do this.

1. You could make the difficulty a class variable (static keyword) then have each scene check the difficulty variable on this script. This would be the opposite of your idea, but would be just as easy, if not easier.

2. You could use DontDestroyOnLoad() on some script in your opening scene so that the difficulty manager is not destroyed when the new scene loads.

3. I am not sure how skilled of a programmer you are, but you could create a singleton of you individual scene managers, and then change the difficulty there.

4. You could use PlayerPrefs to store a value to load in the next scene. This method is not really ideal, and I would only use it if the other 3 fail.

The problem is that instances of your scripts are created and destroyed when a scene loads, not when the game loads, so you either have to create a class field or singleton or use DontDestroyOnLoad.

There are 2 straight forward answers that I can think of.

1. Make all members in the class static. Making them static is super easy and convenient, but there are a couple problems that you run into: 1, you can't have more than 1 of a member, because static members belong to the Class and not the instance of a class. 2, Unity does not support editor drag and drop functionality of static members ([serilizefield] or public functionality). There are probably some fancy things you could do to get around that, but it's not straight forward. If you must have this,

2. Make a Singleton helper. a class that calls the singletons methods. The most standard way to make a Singleton is to make a public static instance of itself like this public static MenuManager instance; void Awake() { if (instance) { Destroy(gameObject); } else { instance = this; } } then in another class call the singletons methods using that instance

   public void DoSomething(){ SingltonClass.instance.DoSomething(); } you can put that class in all your scenes, but you only need to put the singleton in your main menu scene, or whatever scene you wish.

I've loadded Settings scene from MainMenu scene, and now both of the scene exists

 SceneManager.LoadScene("Settings", LoadSceneMode.Additive);

I've a game object in MainMenu scene on which MainMenuController monobehavior is attached. Now, in SettingsController.css, I can call a function inside MainMenuController.cs

 function void SomeFunc() 
 {
     MainMenuController mainMenuController = GameObject.Find("MainMenuController").GetComponent<MainMenuController>();
     
     mainMenuController.DoSomething();
 }

Peter says that he doesn't suggest PlayerPrefs method to use. Can anyone tell me why i should avoid to use this method ?

I think, it would be easier to save variables and then call it on anywhere you like... I'm not sure though...