So far as I know there’s only one useful app for Level II – Allen’s CFA Review.
Relatively cheap ($35 to unlock the full qbank through June)
Has all the topics covered
Can create custom quizzes with just the topics you want to do
Has rankings so you can see how you stack up against the several hundred other users
Customer support responds within a day
Some questions are not fully updated for 2015 (e.g. some of the language is dated, and some are on LOS no longer tested to my knowledge)
Since their Qbank lets you have up to 5 answer choices per question doing quizzes with 3 (as per the actual exam) sometimes makes the right answer very clear or, alternatively, more confusing.
The point of an iPhone app to me is to cover the more qualitative and conceptual questions (because I’m not going to bust out my BAII and a notepad while waiting in line for coffee) and there’s no way to pick out just those (although you can skip questions without penalty during a quiz)
If anyone knows of any other good apps (for iOS or Android) I’d be curious to know as well. A current flashcard app especially would be great. Sadly most of the best-made apps are for Level I only from what I’ve seen.