According the docs:
In iOS 6 and later, if you assign a value to this view’s restorationIdentifier property, it attempts to preserve its URL history, the scaling and scrolling positions for each page, and information about which page is currently being viewed. During restoration, the view restores these values so that the web content appears just as it did before.
I'm doing all that, but nothing is happening. And even if I manually save and restore the URL the user was looking at previously, the scroll position is not restored. Are the docs just wrong?
I have tried Matt's answer and it works well, however if there are 'forward' pages in the history stack-they will be replaced by the restored request within the web view object.
A better approach is to instead call the 'reload' method on the webview object, this will restore the history in both directions as well as the zoom and content scroll offset.
If you'd like an example of my approach or some more functionality for your own webview, take a look at my open source fork of SVWebViewController here.