Support for iWorks' Pages, Numbers, and Keynote version of snappy framed.

[ronaldmannak]

I noticed you already included a stub for snappy framed. I would love to see support for, what I understand, Apple's slightly non-standard version snappy framed Apple uses to compress the .iwa files inside Pages, Number, and Keynote files. Even snzip can't decompress .iwa files in the latest file formats anymore.
This feature would be a lifesaver, as it finally opens up Apple's iWork format to Swift developers.

[RandomHashTags]

Absolutely would support it. If you can provide any information (or any .iwa files) about how it works or any modifications of Snappy Framed it uses, that would significantly help out in getting a working version developed.

[ronaldmannak]

Unfortunately I don't think there's much recent info available. This fork updated for the 2014 format update. There is some information here on the 2013 format and some specs here.
However, Apple might have changed the format since, because I wasn't able to use the old tools and code (I might have done something wrong though).
I just stumbled upon a few other projects:
pyiwa and tika and an interesting comment to remove the first 4 bytes I might try out later.

So I'm there will be some trial and error involved

[RandomHashTags]

I think snappyFramed should be fully developed first (and add a protocol buffer compressor/decompressor) before we start Apple's port of it.

The current Snappy implementation only supports decompression, with no work on Snappy Framed yet. PRs a very welcome as I want to prioritize other compression techniques and features, but I will eventually get around to it (hopefully soon).

I will add some placeholder logic where it should live.

[ronaldmannak]

Sounds like a plan. Thanks!

[RandomHashTags]

Progress update (for reference):

• we can use swift-serialization for the protocol buffer compression/decompression

Last things to do:

• finish Snappy compression (currently only partially implemented)
• implement Snappy Framed (maybe modify Snappy to indirectly support?)
• implement iWA