ios webview caching

Partial work for @imurchie to take over.
I understand what args is.  I guess if it's clear in the docs.  On first glance, I expected "callbackAddress" to be a callback. It looks like a non-function (this.args.address) might get assigned to what is intended to be a function pointer, which alarmed me. After a second I realized what was going on, but my rule of thumb is that if the reader has to think, you prolly need a comment. Not a huge deal here, tho, if you feel otherwise.