Add this attribute to a method to get a notification just before building the scene.
// C# example:
// Automatically creates a game object with a primitive mesh renderer and appropriate collider.
using UnityEngine;
using UnityEditor;
using UnityEditor.Callbacks;
public class MyScenePostprocessor {
[PostProcessScene]
public static void OnPostprocessScene() {
GameObject cube = GameObject.CreatePrimitive(PrimitiveType.Cube);
cube.transform.position = Vector3(0, 0.5, 0);
}
}