how to imp the outlineVIew custom group header view?

[liufsd]

i have try to imp the outlineView ,if the outlineView has not set headerCell ,the goupCell will show "show/hide" action on right. but i want imp it to show exp/colls on groupCell left like has set headerCell . By the way, i found that the outlineVIew's child cell not show on screen left. i mean it will show a padding on the left.how to fix it ? How to imp it ? Do you have any idea about? Thanks.