Lately, I've had the need to work offline way more than usual due to a spotty connection. I thought it'd be pretty much impossible to work this way, but I found out that it's quite the contrary.
It's not so bad
I don't really miss it as much as I thought I would. I can make a mobile application from start to finish (with a few caveats) without a working internet connection. Most of my reference materials are in my previous projects (that are already on my Mac) and for the rest, I usually can recall it from the top of my head. For what I can't, I prepare detailed notes on what to look up when I get back online and skip/mock it away so I still have a working application with a few parts pending. That's the beauty of compartmentalization. Each part of the application should work as its own unit in isolation.
The biggest problem I found is is installing dependencies or making a build. Those issues don't depend on me though, but the fact that you can't build in Xcode (most of the times) without being connected to the internet is backward.
I'm NOT advocating to work offline.
It's a huge waste of time and you do it only when you really can't do otherwise. But when you are without connectivity, you can still be productive and build applications without a connection. You will just be slower and probably will need to go back online to add the finishing touches and distribute it.