For my entire time at Planning Center we've never had an official style guide. Just lots of existing code to serve as our guide. Today, that all changed.
One of the challenges of Music Stand is rendering PDFs and user annotations in a timely fashion. Each of those tasks alone isn't a big deal, but all together it's quite a challenge. Let's take a look at how Music Stand renders and caches PDF pages.
Each of the iOS apps at Planning Center make heavy use of Core Data. We don't use it in the traditional sense of the users data store. Instead, we use it as a cache. Using Core Data as a cache allows us to display pre-fetched data to a user. It speeds up interactions for the user and gives us compile time checking for data access.