[css]

iMessage uses a very strange amalgamation of typedstream (message content), keyed archives (app messages, sticker data), and protobufs (Digital Touch, handwriting) for different features. I wonder what motivated all of those design decisions.

[bengarney]

This is stuff is such a PIA to parse. I assume it's just different teams doing different features over the years, and being alternately repulsed/seduced by each format. Probably features are implemented as libraries so there isn't a master oversight - they aren't trying to make iMessage's internal formats follow a consistent plan, just let all the libs coexist...

[meibo]

Maybe they should be repulsed, considering all of the journalists that are getting persecuted and/or murdered because they are getting pwned through iMessage serialization bugs :)

[pixel_tracing]

As someone who used to work on that team, it’s so interesting hearing thoughts from external public on the team.

[ajtaylor]

I would love to hear your thoughts as an insider.

[userbinator]

"Those who don't understand ASN.1 are doomed to reinvent it, poorly."

That said, it could be much worse --- JSON, or XML.