iPhone local web applications

Startlingly, the webkit-based browser on the iPhone supports the HTML 5 client-side storage standard. Alas, you can’t write properly off-line apps because there’s no local HTML/file cache on the phone you can keep files in. You could use the bookmarklet trick I suppose, but I don’t like that one – it’s nasty, and makes development annoying – you have to keep re-syncing things, it’s not terribly easy to upgrade, etc.

I do, however, want to write local apps in a language that’s a little higher-level than Objective-C. It’s nice and all, but I prefer things to be more flexible. The iPhone SDK agreement means that I can’t write my code in a high-level language and ship an interpreter, alas – no iPhone pyobjc for me. But (and this is speculative, I’m not a lawyer, etc etc) as I read the iPhone SDK user agreement, I think you could probably write a pure HTML/JavaScript application, using the webkit local storage engine, and run it in an embedded webkit view as a local iPhone application.

3.3.2. [..] No interpreted code may be downloaded and used in an Application except for code that is interpreted and run by Apple’s Published APIs and built-in interpreter(s).

(emphasis mine)

This means I can have a shippable application, with local storage, but with large bits of logic written in JavaScript. I may even be able to intercept requests for urls and call API functions from Objective-C space, so I can expose location data to the application, for instance.

There are obviously huge disadvantages to writing an app in HTML, but I’d like to try it if only as both a rapid prototying environment for local apps, and a way of giving apps that are already HTML-based some local storage and the ability to be run when away from network.

Unfortunately, I feel that I can see where this could get taken. The spirit of the SDK agreement is clearly that Apple don’t want any way of distributing applications except through the App Store. This exception is in the SDK only because you can’t have an embeddable web browser widget without saying ‘stuff the web browser does is ok’. But if this loophole actually is a loophole, I don’t see what stops me writing a front-end that can download more HTML into the local storage area.

Well, no, actually, I see

3.3.3 Without Appleā€™s prior written approval, an Application may not provide, unlock or enable additional features or functionality through distribution mechanisms other than the App Store.

..which might cover that one. Maybe I’ll write something like this as an experiment anyway.

Here’s another thought. If I can intercept requests and call Objective-C functions, why do I need the HTML-displaying part of this at all? How introspectable is Obj-C anyway, and can I ship an Objective-JavaScript bridge in my app?