Cocoa equivalent of diskEvt/kEventClassVolume?

We have a drop-down menu of volumes in our UI, and I'd like to update it when a new disk is mounted. In the 开发者_StackOverflow社区Classic days, this would involve watching for a diskEvt event. In Carbon, I think this was kEventClassVolume. What's the Cocoa equivalent?

(A pointer into Apple's documentation on this would satisfy the question. I've been unable to find anything!)

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NSWorkspace posts NSWorkspaceDidMountNotification and friends on its notification center.

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Disk Arbitration is responsible for those notifications. It's not written in Cocoa.