Carto is an open source small editor for Google Sitemap files. It allows you to create, change, batch edit, and search page settings for a sitemap file. Carto imports (and of course) exports sitemal.xml files.

You can also drag-n-drop URLs from a web browser, or fetch the current modification date for an URL by querying the web server. Carto also handles redirects and updates the page URL as needed.

Carto's source code is also an example for a simple Core Data application, with a short example of Web Kit / Foundation URL loading code, and an array controller customized for drag-n-drop.