My iPhone (actually, iPad) app creates documents that consist of several images, plus a bit of metadata. What's the best practice for storing these sorts of documents on disk? I see two main options:

1. Create a folder for each document, and store my images as separate PNG files within the folder (plus another little file for the metadata).

2. Create a single file which contains all images and metadata.

But I'm not sure how to easily do option 2. I think I can convert my images in PNG format to/from NSData, but then what? I'm still a newbie at Cocoa, but I believe I saw something about stuffing mixed data into some NSSomethingOrOther and having this write itself out to disk, and read itself back in later. Does this ring a bell with anyone? And, will it work with large binary blobs of data like my images?

Or would you recommend I simply go with option 1?