How did I not know about this? iOS in-app debugging, including network calls, view hierarchy, and basically anything else you can think of. On the device! No Xcode needed.
FLEX (Flipboard Explorer) is a set of in-app debugging and exploration tools for iOS development. When presented, FLEX shows a toolbar that lives in a window above your application. From this toolbar, you can view and modify nearly every piece of state in your running application.
Via iOS Dev Weekly.