If you use the
NSCodingprotocol on your model classes to create
NSKeyedArchiverarchives, you know that
NSKeyedArchiveruses some strange binary format by default. If you try to examine an archive file, you'll see a lot of binary gibberish starting with "
bplist00". This is actually a binary version of Apple's common XML Plist file format.
Archive files aren't exactly easy to grok since they contain a lot of meta-data like the classes of objects in the archive and the relationships between objects, but being able to look at the XML can sometimes be a big help when debugging. And TextWrangler automatically does the right thing with them.
TextWrangler is available in the Mac App Store and I highly recommend it.