I am using Cocoa with Obj C. I am working on XCode 2.4.1 I am having a NSArrayController object which holds a class Collections. Collections class is having different member variables and associated methods. "Type" is one variable in that Now I am using this NSArrayController object and binding it to NSTableView to populate necessary data in it. Now I want to change this to NSTableView to NSOutlineView so that I can have tree structure inside it. By using "Type" in my class object, can I bind (or some other method) to populate my NSOutlineView and show the classified data depending on "Type" For eg: Fruits Apple Banana Flowers Rose Lilly Birds Pegion Crow . . . Here Fruits, Flowers, Birds etc are "Types" in my Collections. Is it possible?