I am trying to learn how to build mobile apps and want to know which codebase you guys think are particularly clean/well-laid out. Preferably ones which have good architectural documentations (or bloggers explaining the architecture).
For example, this guy does a lot of code reviews for open sourced games/game engines: http://fabiensanglard.net.
He has a very good code review of DOOM on iPhone: http://fabiensanglard.net/doomIphone/index.php.
Particularly insightful blogs on how to architect modern mobile apps (even if it is closed source) are also welcomed. For example Dropbox's tech blog on how they structured the code for their photos app:
https://tech.dropbox.com/2014/04/building-carousel-part-i-how-we-made-our-networked-mobile-app-feel-fast-and-local/
It is a high quality and popular vector drawing app (4+ stars on app store) and the code is clean and simple to understand. I am not sure you will learn anything by just reading through it if you're not building a similar kind of app though.
Quick googling also yielded these lists:
http://maniacdev.com/2010/06/35-open-source-iphone-app-store...
http://en.wikipedia.org/wiki/List_of_free_and_open-source_iO...
How to architect your app really depends on what kind of app you're building.