I believe you can start form UISplitViewController which was drastically updated in iOS8. Watch sessions View Controller Advancements in iOS8 and Building Adaptive Apps with UIKit for details. They provide code example from second session (but not form first one :/). At this point it feels natural for me to make this kind of UI based on split view controller in iOS8.
Update: It looks like not all API they talking about are landed yet. In current beta4 mentioned in video condensesBarsOnSwipe is not presented, for example.