How to implement the folder tree in the left of finder?

I just like to implement a function : Develope a app , and have a outli开发者_如何学Pythonne view, which have a folder and file tree just like Finder or a app called PathFinder , how to implement it ? Thank you very much!

That's called a source list, and there's a really convenient NSOutlineView subclass available on github here: http://github.com/Perspx/PXSourceList