Building iOS Web Apps in 2013
TL;DR: iOS 6 brought many new great features for web apps, modern iOS devices are insanely fast and I now consider web apps to be a robust alternative to developing native apps.
- Safari's Web Inspector support
- camera access
- CSS Filters
And you can obviously keep using all the great things already implemented in iOS 5 such as Web Workers (to keep the UI responsive while doing intensive operations) and App Cache (to run your app offline). It's also fairly easy to save the current app state using Local Storage so we can display the exact same view as the previous launch, including scroll positions and, for example, a piece of text being entered by the user. Really, there isn't much that prevents us from reaching a native-like experience.
Developing web apps for iOS today is just a fantastic experience. You have great tools, great performance and great resources, it's up to you to write great code and to care about the user experience. And if you do, I'd suggest considering web technologies for your next mobile app (be it only for the auto-update) unless you need OS-specific APIs, such as accessing the user's Contacts or sending push notifications. Happy coding!