Undo.RegisterCreatedObjectUndo

Parameters

Description

Registers an undo operation to undo the creation of an object.

This method registers the creation of an object to the undo stack so that users can undo a create object action. Use this method each time you define an action that creates an object, for example, inside a custom Editor or menu item. Unity updates the undo action in the Edit menu with the name of the undo operation. When the user performs the undo action, Unity destroys the object.

Note: The undo process destroys objects in the same way as Object.Destroy, but with no delay.

When you create and modify an object at the same time, use the following workflow to ensure that Undo.RegisterCreatedObjectUndo saves all updates to the object:

1. Create the object.
2. Register the object as created with Undo.RegisterCreatedObjectUndo.
3. Register the object with Undo.RegisterCompleteObjectUndo so that the Editor records changes to the object. If the object has any child GameObjects, register it with Undo.RegisterFullObjectHierarchyUndo instead.
4. Update the object.

If you do not follow this workflow, Undo.RegisterCreatedObjectUndo might not save any updates to the object other than object creation.

When you register a new object with Undo.RegisterCreatedObjectUndo, Unity registers any changes to objects that are currently recorded by Undo.RecordObject and then stops recording. This means that after you register a new object, Unity does not record any subsequent changes to any other objects that Undo.RecordObject was already recording.

When Unity is already recording changes to existing objects with Undo.RecordObject and you want to register newly created objects, it is best practice to follow this workflow:

1. Complete any changes you want to make to objects that Undo.RecordObject is recording. Unity calls Undo.FlushUndoRecordObjects automatically.
2. Register newly created objects with Undo.RegisterCreatedObjectUndo.

If you do not follow this workflow, Unity might not store the state of the recorded objects on the undo stack correctly.

The following example shows how to create and modify a GameObject with a child as an operation that can be undone in a single undo step.

using UnityEditor;
using UnityEngine;

class CreateGameObjectMenu
{
    [MenuItem("Example/Create GameObject")]
    static void CreateGameObject()
    {
        // Create new undo group
        Undo.IncrementCurrentGroup();

        // Create GameObject hierarchy
        GameObject go = new GameObject("my GameObject");
        Undo.RegisterCreatedObjectUndo(go, "Create my GameObject");
        GameObject child = new GameObject();
        Undo.RegisterCreatedObjectUndo(child, "Create child");
        Undo.SetTransformParent(child.transform, go.transform, "Modify parent");

        // Move GameObject hierarchy
        Undo.RegisterFullObjectHierarchyUndo(go, "Update my GameObject position");
        go.transform.position = new Vector3(5, 5, 5);

        // Name undo group
        Undo.SetCurrentGroupName("Create and Reposition GameObject with Child");
    }
}

Note: This operation cannot be performed when isProcessing is true.