iCal, MobileMe and Synchronisation

In a previous post I mentioned using Calendar events to automatically download podcasts over night. When I set this up I just added an Events calendar (to keep this daily repeating event separate from everything else so that I could filter out its view).  However this was still within my MobileMe Calendar.  This meant that this calendar and its events was being synchronised to my other Mac computer and also to my iPad and iPod touch.  This was annoying for two reasons:

  1. It added an item to every day on the calendar which while a little annoying on my iMac wasn’t too bad as it could be filtered, but was really annoying on my iPod Touch and IPad where it is more difficult to filter calendars.  (As far as I can tell you can display all calendars, or an individual calendar, but can’t filter out individual calendars.)
  2. The associated event also appeared so that on my iMac I would get an error message each day saying the event hadn’t run because the script couldn’t be found.  On the iPod Touch and iPad a notification for the event would come up on the device.

The answer to this problem is not entirely trivial.  The new MobileMe calendar is effectively stored in the cloud and distributed to devices and as far as I can see you get all of it subject to some filtering on the iOS devices where events beyond a certain point in the past are not synchronised.  Therefore this event/action for executing the script needs to be in a local calendar.  This can be done by creating a new calendar in the “On My Mac” group:

iCal Menu Screenshot


I moved the Events calendar from my MobileMe group to the On My Mac group (and also renamed it to Alarms — Autorun).

Calendar on iCal

However, I discovered that this didn’t quite solve the problem as this calendar also become synchronised to my iMac.  To solve this one needs to go in to the MobileMe preferences and on the Sync tab un-check Calendars.  The Mobile Me calendars are still synchronised as these have a master slave relationship between MobileMe in the cloud and the individual devices.  Un-checking this box stops the local “On My Mac” calendars being synchronised between machines.

Synchronisation Preferences

This means that the local “Alarms — autorun” calendar now stays firmly on my MacBook which is where I keep my main iTunes Podcast library.  The next time one opens the calendar on an iOS device these events and alarms will disappear as they are syncing through the cloud MobileMe.

I imagine that you need to make sure that you are not synchronising calendars to iOS devices via iTunes.  However, if you are using MobileMe you probably shouldn’t be using iTunes syncing for calendars in any case as it should be the cloud syncing (and if you have both, the calendars probably have multiple entries!)

I’m not sure if this helps anyone else, but at least it is a record for me when in six months time I’ve forgotten what I did.


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