Can I share a calendar event with another iPhone user?
In the Calendar app , you can share an iCloud calendar with other iCloud users. When you share a calendar, others can see it, and you can let them add or change events. You can also share a read-only version that anyone can view but not change.
Why can't I share a calendar event on iPhone?
When you create a reminder, you can choose to store it in iCloud or on your iOS device. If iCloud is not your default for Calendars, you'll be unable to add invitees.Jul 9, 2018