This looks very handy but I can't get it to work so I think I'm doing something wrong. Are the calendars mentioned the ones at apple.com/downloads/macosx/calendars? If so, is the web address of the particular calendar I choose what I put in the settings? I tried this and it says "Unable to verify account information." Can anyone clarify please?
I've found this method to work fine, when it does; and not at all when it does not.
Visit the page in Safari on the iPad. Tap the download button on the page. One of two things happens. You go to a special php page where you can subscribe to the calendar, or it's downloaded in Safari and you get the Open in Calendar option for the attachment.
In the first case you just make sure the settings (if any) are what you want and tap the Subscribe button on that page.
In the second case you'll be taken to Calendar and offered the option of adding all or some of the events.
Or it just won't work.
If you decide you don't want the calendar after all you will 'probably' need to visit Settings > Mail, Contacts, Calendars and open the Subscribed Calendars account. Deleting it from inside the Calendar app does not alway remove the new calendar permanently.
If you know the URL to subscribe to the calendar you can also try and add it as an account. I'm thinking that is what you were trying. Again, success varies, and all I can suggest is play around and see what it does. You can always remove unsuccessful attempts.
I've only played with this for a an hour or so. That means there are probably other surprises and better ways of doing things than I saw.