The POPSpringAnimation can be replaced by [UIView animateWithDuration:delay:usingSpringWithDamping:initialSpringVelocity:options: animations:completion:], which allows you to create spring animations that are very similar to those of a POPSpringAnimations. The advantage of this though is that 1. there is no need for a big 3rd party library (pop), and 2. It isn't tied to CALayers but you can also animate a UIView this way. The fact that the button would no longer rely on pop is a big deal. Pop is a massive library compared to this tiny button library. I really hope that you consider removing pop in favor of the UIKit spring animation. I would be glad to help updating the code!
The POPSpringAnimation can be replaced by
[UIView animateWithDuration:delay:usingSpringWithDamping:initialSpringVelocity:options: animations:completion:], which allows you to create spring animations that are very similar to those of a POPSpringAnimations. The advantage of this though is that 1. there is no need for a big 3rd party library (pop), and 2. It isn't tied to CALayers but you can also animate a UIView this way. The fact that the button would no longer rely on pop is a big deal. Pop is a massive library compared to this tiny button library. I really hope that you consider removing pop in favor of the UIKit spring animation. I would be glad to help updating the code!