caching web service calls in MonoTouch

In Objective-C, I've used Three20's TTUrlRequest to enable some simple caching of my web service calls.

I'd like to do something similar in MonoTouch, but it's unclear whether or not the MT implementation of HttpWebRequest supports caching. Using HttpWebResponse.IsFromCache causes a "Not 开发者_开发百科Implemented" exception.

I haven't been able to find any good discussions on caching strategies when using MonoTouch.

Is there any built in caching support, or do I have to roll my own?

I suspect that they haven't implemented WebRequest.CachePolicy in MonoTouch.

I think you'd be better off implementing your own caching, as you could invalidate your cache on demand--such as after modifying the data from the iPhone or by some other event.

You also get to pick your storage mechanism as SQLite, xml file on disk, etc.