The document describes how to use events in the SceneManager to get notified when the active scene changes or a scene loads. It provides an example script that subscribes to the activeSceneChanged event to print the previous and next scenes. It also shows subscribing to the sceneLoaded event to call a custom method when a scene finishes loading. The example demonstrates adding and removing event handler methods at appropriate times in the game object's lifecycle.

1. SceneManager.activeSceneChanged
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Parameters
value Previous active scene and the new active scene.
Description
Subscribe to this event to get notified when the active Scene has changed.
This script added to activeSceneChanged takes two hidden arguments. These are the replaced
Scene and the next Scene. The arguments are not visible.
In the Editor this event is sent only in Play mode (not in Edit mode). If the event is needed for Edit
mode then use EditorSceneManager.activeSceneChanged.
// SceneManager.activeSceneChanged
//
// This example configures Scene1 to wait for 1.5 seconds before switching
to Scene2.
// Scene1 is the replaced scene; Scene2 is the new loaded scene.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.SceneManagement;
public class ScriptExample1 : MonoBehaviour
{
public delegate void Change();

2. public static event Change TimeChanged;
public void Start()
{
SceneManager.activeSceneChanged += ChangedActiveScene;
// wait 1.5 seconds before change to Scene2
StartCoroutine(TimeChangedScene());
}
IEnumerator TimeChangedScene()
{
print(Time.time + " seconds");
yield return new WaitForSeconds(1.5f);
print(Time.time + " seconds");
// call the event
TimeChanged();
}
private void ChangedActiveScene(Scene current, Scene next)
{
string currentName = current.name;
if (currentName == null)

3. {
// Scene1 has been removed
currentName = "Replaced";
}
Debug.Log("Scenes: " + currentName + ", " + next.name);
}
void OnEnable()
{
Debug.Log("OnEnable");
ScriptExample1.TimeChanged += ChangeScene;
}
void ChangeScene()
{
Debug.Log("Changing to Scene2");
SceneManager.LoadScene("Scene2");
Scene scene = SceneManager.GetSceneByName("Scene2");
SceneManager.SetActiveScene(scene);
}
void OnDisable()

4. {
ScriptExample1.TimeChanged -= ChangeScene;
Debug.Log("OnDisable happened for Scene1");
}
}
ScriptExample2 simply announces that this is the active scene.
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
public class ScriptExample2 : MonoBehaviour
{
void Start()
{
Debug.Log("Script2 starting");
}
}
SceneManager.sceneLoaded

5. Other Versions
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Description
Add a delegate to this to get notifications when a Scene has loaded.
Rather than being called directly this script code shows use of a delegate. This means
the sceneLoaded value is added into a list of delegates.
In the script example below a number of method calls are shown. Specifically the first labelled
method OnEnable() is used to add OnSceneLoaded (), which is not a Unity provided method.
The SceneManager.sceneLoaded delegate can have any method hooked into it and it is
OnSceneLoaded () here. Finally, OnDisable() is used to remove OnSceneLoaded ()
from SceneManager.sceneLoaded.
using UnityEngine;
using UnityEngine.SceneManagement;
public class ExampleCode : MonoBehaviour
{
// called zero
void Awake()
{
Debug.Log("Awake");
}
// called first
void OnEnable()
{
Debug.Log("OnEnable called");

6. SceneManager.sceneLoaded += OnSceneLoaded;
}
// called second
void OnSceneLoaded(Scene scene, LoadSceneMode mode)
{
Debug.Log("OnSceneLoaded: " + scene.name);
Debug.Log(mode);
}
// called third
void Start()
{
Debug.Log("Start");
}
// called when the game is terminated
void OnDisable()
{
Debug.Log("OnDisable");
SceneManager.sceneLoaded -= OnSceneLoaded;

7. }
}