Researching file formats 34: iOS App Store Package

This blog post is part of a series on file formats research. See this introduction post for more information.

Update: The official format definition is now online here: IPA. Comments welcome directly to the Library of Congress.

Like last week’s post on the Android package, the iOS App Store Package is also… (dun dun dun)… just a ZIP archive file!

It’s also not really well-disclosed, with no official docs from Apple that specify the .ipa file as a format.

Structured like this:

According to this Apple documentation initially created at 2014-03-06, there are several types of .ipa files, which I’ll summarize:

LC’s Recommended Format Statement defines this as a “distribution file”, stating “Distribution file (e.g. ipa [Mac iOS], apk [Android], exe [Windows]): The distribution file is disseminated for public use regardless of the means of dissemination (on physical media or via an online source) and is comprised of one or more files from the gold standard build.

We all know Apple loves the “technical protections considerations” category, so this is a can-o-worms. There’s FairPlay, and the way it works out is a bit interesting, but I’m not going to get into it here – I yawned while typing that, so I guess I’m lying about it being interesting, I was just using a generic word to describe it when I didn’t have anything noteworthy!