Took a quick browse through your iOS codebase, and I gotta say that I am not impressed. This app seems to follow the classic "massive view controlller" architecture, where a ton on unrelated functionality is squeezed into the controller. On top of this, I see very little unit testing at a controller layer. This is a dangerous combination where some of the most complex part of you codebase has some of the least test coverage.

You might want to consider patterns like MVVM to bring your controllers under control and increase your test coverage.