Apple introduced a new UI in Apple Music on iOS 8.4.
When an audio track begins to play, a miniplayer appears just above the tab bar, and it can be brought into full screen mode my dragging it up or tapping on it.
I imagine this is using the UIViewController containment APIs. Where can I start with my own implementation?
How might I implement something similar?
Funnily enough, I came across a framework that implemented this earlier this week. Give LNPopupController a look. It implements the behavior you're looking for (showing a mini bar, then tapping or dragging to present a view controller). If it doesn't quite fit your needs, maybe it can at least provide a starting point for you to implement your own thing.