PanelKit is an open source framework from Louis D’hauwe that allows you to create panels within iOS that can be presented modally, floated, dragged or pinned.
The Panels created with PanelKit can be resized, and this makes it very easy to create a UI. You can easily code new panels which the user can then add to the view.
This animation shows PanelKit in action:
You can find PanelKit on Github here.
A nice library for anyone looking to implement a “Windows” style interface within an iOS app.