SwitchLayerRecursively

using UnityEngine;

public static class LayerHelper
{
    public static void SwitchLayerRecursively(Transform transform, int layerID)
    {
        SpriteRenderer sr = transform.GetComponent<SpriteRenderer>();
        if (sr)
            sr.sortingLayerID = layerID;
        foreach (Transform t in transform.transform)
        {
            sr = t.GetComponent<SpriteRenderer>();
            if (sr)
                sr.sortingLayerID = layerID;

            SwitchLayerRecursively(t, layerID);
        }
    }

}