Turn on iCloud, Google, Exchange, or Yahoo! calendars.
Go to Settings > Mail, Contacts, Calendars, tap an account, then turn on
Calendar.
Subscribe to a calendar.
Go to Settings > Mail, Contacts, Calendars, then tap Add Account. Tap Other,
then tap Add Subscribed Calendar. Enter the URL of the .ics file to subscribe to.
You can also subscribe to an iCalendar (.ics) calendar by tapping a link to the
calendar.
Add a CalDAV account.
Go to Settings > Mail, Contacts, Calendars, tap Add Account, then tap Other.
Under Calendars, tap Add CalDAV Account.
Add an OS X Server account.
Go to Settings > Mail, Contacts, Calendars, tap Add Account, then tap Other.
Under Servers, tap Add OS X Server Account.
View the Birthdays calendar.
Tap Calendars, then tap Birthdays to include birthdays from Contacts with your
events. If you set up a Facebook account, you can also include your Facebook
friends’ birthdays.
View the Holidays calendar.
Tap Calendars, then tap Holidays to include national holidays with your events.
See multiple calendars at once.
Tap Calendars, then select the calendars you want to view.
Move an event to another calendar.
Tap the event, tap Edit, tap Calendars, then select a calendar to move it to.