Animations and transitions are decisively one of SwiftUI’s fortes. The framework allows us to go as deep as we want in handling specifics like timing function and duration parameters. Moreover it gives us sophisticated tools like the Animatable protocol to completely customize behavior. Here we are going to rely on the more constricted AnimatableModifier protocol to show how we can manually pause and resume and animation as well as adding the ability to reverse and loop over.

Scroll views in SwiftUI are very straight-forward but give us no information or control over the current position of its content. So how can we detect for instance that the user has scrolled beyond certain threshold off the top?