How to edit a subscribed calendar on iPhone, iPad or Mac

Why you can't edit it

A subscribed calendar (a link ending in .ics, or one that starts with webcal://) is read-only. Your iPhone downloads a fresh copy every so often and replaces whatever is there, so Apple doesn't let you edit it. Google Calendar and Outlook do the same with calendars added "from URL".

The usual workarounds don't last. Copying events by hand misses every change the organizer makes. Importing the file once gives you a copy that never updates.

The fix: keep the feed, edit a copy

Calendar Corrector reads the calendar you subscribe to, applies your changes, and writes a corrected copy into a calendar of its own. When the original changes, the copy updates too, with your changes still applied.

1. Install Calendar Corrector and tap Add a calendar.
2. Pick the subscribed calendar from the list, or paste its link.
3. Tap any event to change its title, time, location, alert or colour. Choose Just this one, or apply it to all events like it.
4. In the Calendar app, untick the original subscription so you only see the corrected copy.

Your original calendar is never changed, and you can undo any fix.