Cocoa left column menu

Several mac app开发者_JAVA百科lications, both Apple and third party, feature a menu in the left column usually used for filtering content. Below are some examples from iPhoto, iCal and iTunes.

I don't see an interface builder class that corresponds to this. How are these usually implemented? A NSTableView with custom cells? Is there any pre-written code to handle the more complex aspects like the collapsing triangles? This seems like a such a common user interface that I don't want to reinvent the wheel if I don't have to.

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