Determine if an IO file is closed on OS X

Question

I want to trigger an event in OS X — maybe from the command line or Obj-C — when IO closes on a specific file (and not on the file).

In linux, this is easy; inotify provides IN_CLOSE_WRITE events.

But in OS X, FSEvent only signals changes in some directories; it does not seem to provide any information on whether the IO is complete.