This repository includes a playground book that can be used with Swift Playgrounds on iPad (recommended) and also a regular Xcode playground. These playgrounds were made to demonstrate some of the techniques I talked about in my "Fluid animations and interactions on iOS apps" talk at BA:Swiftable.
I also recommend reading this excellent post by Christian Schnorr to learn more about the math behind these techniques.
This open-source sheet implementation can also be used to learn more about iOS interactions and animations.