Working with Files(Chapter 16 of Programming in Objective-C 2.0)

　　A file or directory is uniquely identified to NSFileManager using a pathname to the file.A pathname is an NSString object that can either be a relative or full pathname.A relative pathname is one that is relative to the current directory.

　　Sometimes you need to get a list of the contents of a directory.This enumeration process can be accomplished using either the enumeratorAtPath: or the directoryContentsAtPath: method. In the former case, each file in the specified directory is enumerated one at a time and, by default, if one of those files is a directory, its contents are also recursively enumerated. During this process you can dynamically prevent

this recursion by sending a skipDescendants message to an enumeration object so that its contents will not be enumerated.