Facebook has open-sourced a lot of stuff recently, but this is what most developers have been waiting for. Developed originally at Push Pop Press, and refined by Facebook, the company has today released its Pop animation framework publicly. Developers can check out the code from the GitHub repository.

The library enables rapid development of rich animations for iOS (and Mac) apps. Although Core Animation, (Apple’s built-in framework) is well suited to fire-and-forget animations, Pop was created to work seamlessly with modern interactive physics-centric user interfaces.

Although the specifics are rather technical, the framework differs fundamentally from Core Animation by working  on the basis of always converging towards a final (malleable) value, which is much more flexible. The springiness and bounciness seen universally in iOS 7 apps nowadays is also built in to the core of the framework.

Developers can use Pop across their application, from adding visual flair to button states to full screen animated transitions and much more. In many ways, Pop offers the functionality that Apple should be offering natively, if it wants to help developers modernize their app’s experiences.

Pop powers all of the animations seen in the widely-praised Facebook app. There’s a lot of behind-the-scenes engineering that took place to create these effects, so developers wanting to replicate some of Paper’s finesse should definitely take a look at Pop.