Checking invisibility of a file
This NSWorkspace extension add the method “isInvisibleFileAtPath:” to NSWorkspace class. To use it just call that method with a valid pathname you will return a boolean telling you if the file is invisible or not. This method is the union of many partial ways of checking if a file is invisible, which are available on forums. This was needed because Mac OS X has many way of making a file invisible. Note that some paths are hardcoded. Those files apparently do not have any invisible flag, yet they are invisible in Finder.