iOS Jumpstart - How much swift do you need to know?

I don't know any Swift yet but I'm an experienced Ruby dev. How successful do you expect someone like me to be with the Jumpstart iOS? Would you expect it would be a struggle or do the docs provide enough guidance to get basics up and running? I'm trying to decide if I must learn Swift first or if I can learn that as I go along.

Everything in iOS (and Android) uses WebViews out of the box, so to get started you don't need to know much at all.

You'll need to know a fair bit if you plan on building native screens. Ray Wenderlich is great if you want to learn iOS to build more native functionality.