We do offer an integration with Google Calendar, which can be synced with iCal. Here is how:
First of all, you need to synchronize GOrendezvous with Google Calendar for it to act as a gateway.
Once your Google calendar is synchronized with GOrendezvous, you enable it with iCal. Here is the procedure to follow:
Open the Settings app on your iPhone or iPad.
Tap Calendars → Accounts.
Tap Add account → Google.
Enter your email address → Next.
Enter your password. If you don't have the latest operating system and are using two-step verification, enter an app password instead of your usual password.
Tap Next.
Emails, contacts, and calendar events are now synced directly with your Google account. To synchronize only the calendar, turn off the other services.
Open the Calendar app on your iPhone to view your Google Calendar events.
Once the connection is complete, you will need to log off and on again on GOrendezvous to trigger the data share.