I’ve been playing around with React Native, an offshoot of Facebook’s React JS framework for native iOS development. It’s nice. React has its own HTML-like syntax for defining UI view hierarchies, and if you change your application state it takes care of redrawing the UI to reflect the change. And because the whole view hierarchy and the state it’s presenting are managed by the React framework, these changes happen extremely fast.
I’m still not sure if it’s worth using React Native, or any abstraction layer, rather than Apple’s own tools and APIs.
React is fantastic for creating complex view hierarchies, and if you’re more used to working with online data via Ajax than Apple classes like NSURLRequest, then voila—you can just use Ajax.