Does it use game engine or just c++ libs? Its UI is concise and smooth.
I think the biggest tool I have is a very tiny library I wrote about 2 years ago with some help from my friend Ramsey Nasser. It's opensource here: https://github.com/stfj/ofxSpriteSheetRenderer although the docs aren't great.
I use OpenFrameworks for all of the ease of getting setup in xcode and some of the event structure, but all of my openGL calls go through that custom library. It handles spritesheets (and on the fly created sprite sheets), rotation, batching, layers, antialiased shape and line drawing, etc. It's how we managed to have RF run so well even on super old devices