NSTableView Make Cell Editable Programmatically

The requirement is something like this, -- Similar to pList , there would be an + button, when user select this, it should make the last row editable,

Any idea how its feasible, i am able to get which row is selected, but not able to proceed further.

Just set the row to be editable via the provided methods.

NSCell *lastCell; // Find last cell
[lastCell setEditable: YES];