objective c - NSOutlineView: How to have different custom color for item with and without child? -

I have a custom sub-class of NSOutlineView that uses Cellfixel as a cell. Some things with children (which represents a group of children)

I have to keep a custom color for the child without the child and another custom color for the items without hair. I tried to convert it to IB, but color changes only for hair items and in the code I can also set a custom color, but can anyone help me only for hair items?

After a thorough research, it seems that the only way to do this is to override attract Do: Methodology NSOutlineView subclass