For years Apple has made available their own and third-party calendar subscriptions on their iCal Calendars site. Now Apple has appeared to have taken their iCalendar subscription servers offline. The servers host iCalendar files which anyone with an app that supports the iCalendar (ICS) standard can subscribe to. iCalendar files can be used in popular apps like Calendar on iOS and OS X and Google Calendars. Subscribable calendars are an easy way for people to add a mass amount of data -- like holidays or sporting team events -- to their planners. Once subscribed, the calendars automatically update when any changes are made on the server side.
I've used two of Apple's own iCalendar subscriptions (for US and UK holidays) in my calendar apps for many years, but over the last few days I've noticed that the subscriptions were showing a refresh error warning icon.
After trying to refresh the calendars manually an error-1 dialog request started appearing.
To be clear, Apple links many calendar subscriptions on its iCal Calendars site. The only ones that are affected, however, are the ones hosted on Apple's own calendar servers (for example, those beginning with: webcal://ical.mac.com/ical/xxxx.ics).
I've reached out to Apple for comment to see if this is a temporary issue or if they'll be shuttering their iCalendar services for good. Users who are currently subscribed to Apple-served iCalendars will still see events in their Calendar apps since the last time it was refreshed. However, if you delete the subscription, with Apple's iCalendar server currently offline, there will be no way to get the entries back.
Update: As of 7pm GMT on 08/21/12 Apple appears to have put their iCalendar servers back online.