We discounted using a web view based library immediately due to the poor performance and lack of control a sandboxed solution like this would present.
Our first POC used pre-interpolated keyframe data to draw and render animation content using the iOS native Core Animation framework. The POC gave us some positive results, however, it quickly became clear that whilst this solution would be efficient, it would consume a vast amount of development time and budget to build a mature and sophisticated engine.
After further research, we evaluated and selected a mature open source library that would enable us to quickly deliver a sophisticated and fully featured native animation engine across both iOS and Android. This decision reduced development time and allowed the Animo Apps creative team to be able to quickly test and develop high quality animations in parallel to our development work.