Instantiating objects only after scene has been loaded

I'm trying to spawn in objects into the scene from a save file. All the logic is done through my "GameManager" script which is a singleton and persists across both scenes. When transitioning from my main menu to the main level, I call

Code (CSharp):

1. SceneManager.LoadScene("main_level");

However, this totally screws up my entire saving and loading methods.

Code (CSharp):

1. public void LoadGame()
2.     {
3.         SceneManager.LoadScene("main_level");
4.         string jsonData;
5.         if (newGame) // Start new game
6.         {
7.             var defaultPath = Application.streamingAssetsPath + "/Default/Default.json";
8.             if (File.Exists(defaultPath))
9.             {
10.                 jsonData = File.ReadAllText(defaultPath);
11.                 gameData = JsonUtility.FromJson<GameData>(jsonData);
12.             }
13.             else
14.             {
15.                 Debug.LogError("Save file is missing at: " + defaultPath);
16.             }
17.         }
18.         else if (File.Exists(path + "/" + saveName))
19.         {
20.             jsonData = File.ReadAllText(path + "/" + saveName);
21.             gameData = JsonUtility.FromJson<GameData>(jsonData);
22.         }
23.         else
24.         {
25.             Debug.LogError("Save file is missing at: " + path + "/" + saveName);
26.         }
27.  
28.         /* Instantiate required objects */
29.  
30.         // Trees
31.         var treeParent = new GameObject("Trees");
32.         foreach (TreeSaveLoad.TreeData tree in gameData.trees)
33.         {
34.             var treeType = oakTree;
35.             switch (tree.type)
36.             {
37.                 case (TreeSaveLoad.TreeType.Redwood):
38.                     treeType = redwoodTree;
39.                     break;
40.                 case (TreeSaveLoad.TreeType.Birch):
41.                     treeType = birchTree;
42.                     break;
43.                 case (TreeSaveLoad.TreeType.Beech):
44.                     treeType = beechTree;
45.                     break;
46.                 case (TreeSaveLoad.TreeType.Pine):
47.                     treeType = pineTree;
48.                     break;
49.                 case (TreeSaveLoad.TreeType.Oak):
50.                     treeType = oakTree;
51.                     break;
52.                 case (TreeSaveLoad.TreeType.Maple):
53.                     treeType = mapleTree;
54.                     break;
55.                 default:
56.                     Debug.LogError("Missing tree type.");
57.                     break;
58.             }
59.             var treeChild = Instantiate(treeType, tree.position, Quaternion.identity) as Transform;
60.             treeChild.SetParent(treeParent.transform, true);
61.             yield return null;
62.         }
63.  
64.         // Call load event
65.         if (EventManager.Instance.e_loadGame != null)
66.         {
67.             EventManager.Instance.e_loadGame.Invoke();
68.         }
69.  
70.         // Call last, after loading is finished
71.         if (EventManager.Instance.e_loadedGame != null)
72.         {
73.             EventManager.Instance.e_loadedGame.Invoke();
74.         }

I'm trying to spawn my trees from a save file, as well as call a few Unity events that will handle other loading methods. However, what I'm seeing is that the scene loads AFTER my loading methods are called, resetting the entire scene and throwing a whole bunch of errors. How do I ensure that I can move across scenes and only begin to instantiate objects after the scene has been loaded?

 

https://docs.unity3d.com/ScriptReference/SceneManagement.SceneManager-sceneLoaded.html

You'll need to subscribe to the sceneLoaded event.

 

As per the docs: "When using SceneManager.LoadScene, the loading does not happen immediately, it completes in the next frame. This semi-asynchronous behavior can cause frame stuttering and can be confusing because load does not complete immediately."

Hook into the sceneLoaded event and call your loading code there.