For apps that also work with network resources, URLs also mean that you can use one type of object to manage items located on a local file system or on a network server.because it stores the names needed to traverse the directory hierarchy to locate the item.mac OS and i OS provide built-in support that makes opening many types of standard file formats (such as text files, images, sounds, and property lists) much easier.

Resource files are commonly used to store localizable content such as strings and images.Apps can use file packages to implement complex file formats that contain multiple distinct files, or a mixture of different types of files.For example, you might use a file package if your file format includes both a binary data file and one or more image, video, or audio files.(You also build string-based paths by concatenating directory and file-names together, with the results stored in a slightly different format than that used by the .An advantage of file reference URLs is that they are less fragile than path-based URLs while your app is running.An archiver object encodes the state of the objects into a stream of bytes that can be written to disk all at once.An unarchiver reverses the process, using the stream of bytes to re-create the objects and restore them to their previous state.