Have you ever set up two iCal calendars, only to later decide you’d rather have them as one? In my case, I had one calendar named Personal and another named Family Stuff. I decided that was a bit redundant, so I wanted to combine the two into one. But, apart from manually switching all events in one calendar to use the other calendar, it’s not immediately obvious how you might merge two calendars into one.
The answer is surprisingly simple; it lies in the File -> Export menu item. Start by selecting (in the Calendars column) the calendar whose activities you wish to move to another calendar, then pick File -> Export. When the dialog box appears, choose a name (by default, it will be the name of the exported calendar) and save location (Desktop is probably fine; you won’t have this file for very long), then click Export.
From here, there are two ways to combine the calendars. You can either drag and drop the exported file into iCal’s window, or you can use File -> Import (and leave the radio button in the Import dialog set to “Import an iCal file”). In both cases, the result will be this dialog box:
The pop-up menu in the middle will let you specify the destination calendar for the imported events; in the shot above, I’ve already chosen my Personal calendar. Click OK and the events will be imported onto the existing calendar. When it’s done, and you’ve verified that the calendar now contains both sets of events, you can delete the unwanted calendar in iCal. Simple, yet not entirely obvious (and not documented in iCal’s help, at least not that I can see).