Get Children of New Scene - unity3d

Question

I have a GameManager script which manages loading scenes, putting characters in the scene, reading map information from game objects, and so on. The GameManager script is set to DontDestroyOnLoad.
I'm trying to figure out how to access objects within my new scene from GameManager after a new scene loads. I'm using the SceneManager.sceneLoaded event to run my "scene initialization" code. Here's the event handler:
void OnLevelFinishedLoading(Scene scene, LoadSceneMode mode)
{
// I want to access GameObjects within the newly loaded scene here
//
// SceneManager.GetActiveScene().GetRootGameObjects() returns
// System.ArgumentException: the scene is not loaded
// I want to do something like this
foreach (MapFeature mapFeature in rootObject.GetComponentsInChildren<MapFeature>())
{
// Do something
}
}
I'm want to get the root level GameObject of the new scene, and then use GetComponentInChildren on that root object in order to dynamically grab various components in the scene and store them in GameManager. However, SceneManager.GetActiveScene().GetRootGameObjects() returns System.ArgumentException: the scene is not loaded
How do I get objects from my newly loaded scene within my GameManager? If there's a better method than getting the new scene's root object and using that to get its children, I'm all ears.

Answer 1

This seems to be possible by a workaround, where the sceneLoaded Event starts a coroutine waiting for the next frame. Relevant snippet below.
For reference, I read this thread on unityforums, recently: https://forum.unity3d.com/threads/scenemanager-sceneloaded-event-when-fired-checking-scene-isloaded-false.429659/
void Awake () {
instance = this;
DontDestroyOnLoad (gameObject);
SceneManager.sceneLoaded += OnSceneLoadedWrapper;
}
void OnSceneLoadedWrapper(Scene scene, LoadSceneMode mode) {
StartCoroutine ("OnSceneLoaded");
}
IEnumerator OnSceneLoaded(){
yield return new WaitForEndOfFrame ();
Scene scene = SceneManager.GetActiveScene ();
int count = scene.GetRootGameObjects ().Length;
string name = scene.GetRootGameObjects ()[0].name;
Debug.LogFormat ("{0} root objects in Scene, first one called {1}", count, name);
}