Apple Calendar supports iCal subscriptions natively. Subscribe to your tvcal feed once and every episode of the shows you follow appears on its air date, on all your Apple devices.
iCal is the open calendar format (.ics) that Apple Calendar, Google Calendar and Outlook all understand. Apple Calendar can subscribe to an iCal link and keep it updated.
Apple Calendar refreshes subscriptions at the interval you choose. On Mac you can force a refresh with View → Refresh Calendars.
On iPhone, go to Settings → Apps → Calendar → Calendar Accounts → Subscribed Calendars and delete it. On Mac, right-click the calendar and choose Unsubscribe.
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