How to change hierarchy order in layout groups through code

I need to be able to change the order of objects in layout groups dynamically. I can change the hierarchy order in the editor while the game runs and the group updates them fine, but I can't figure out how to do this through code.
I know that hierarchy works with transform z position but in a group the transform of the child objects is driven by the group, and they all have z at 0 anyway...

 

Check out the api docs for Transform. Look for stuff with "Sibling" in the name, e.g. Transform.SetLastSibling, SetFirstSibling, SetSiblingIndex.

 

something like this maybe

Code (CSharp):

1. using UnityEngine;
2. using System.Linq;
3. public static class GameObjectExtensions
4. {
5.     public static void SortChildren(this GameObject gameObject)
6.     {
7.         var children = gameObject.GetComponentsInChildren<Transform>(true);
8.         var sorted = from child in children
9.                      orderby child.gameObject.activeInHierarchy descending, child.localPosition.z descending
10.                      where child != gameObject.transform
11.                      select child;
12.         for (int i = 0; i < sorted.Count(); i++)
13.         {
14.             sorted.ElementAt(i).SetSiblingIndex(i);
15.         }
16.     }
17. }
18.  

Code (CSharp):

1. gameObject.SortChildren();

 

Ok that lets me change the order, but the layout group does not update immediately..
edit: I meant to say, I see the updated order in the layout group only after calling setactive false and true again. There is probably a simple solution to this that I can't find either.

 

You should submit a bug and use layout.enabled false/true or setActive false/true as a workaround meanwhile.

Edit: Or setting parent again for element you changed order (element.trasform.parent = element.transform.parent) which is probably more efficient as a workaround. Which also means that unity for some reason doesn't check if parent really changed calling transform "change" callbacks.

 

I had the problem; the new order of the silbings wasn't instantly reflected by the grid layout. Was able to solve this by using:

Code (CSharp):

1. LayoutRebuilder.MarkLayoutForRebuild(silbingGameObject.GetComponent<RectTransform>());