RiCal is a new Ruby Library for parsing, generating, and using iCalendar
(RFC 2445) format data.

RiCal distinguishes itself from existing Ruby libraries in providing
support for

Timezone components in Calendars. This means that RiCal parses VTIMEZONE
data and instantiates timezone objects which can be used to convert
times in the calendar to and from UTC time.  In addition, RiCal allows
created calendars and components to use time zones understood by TZInfo gem
(from either the TZInfo gem or from Rails ActiveSupport => 2.2).
When a calendar with TZInfo time zones is exported, RFC 2445 conforming
VTIMEZONE components will be included, allowing other programs to process
the result.
Enumeration of recurring occurrences. For example, if an Event has one
or more recurrence rules, then the occurrences of the event can be enumerated
as a series of Event occurrences.

WWW: https://github.com/rubyredrick/ri_cal