eventkit

eventkit covers creating, reading, and managing calendar events and reminders with EventKit and EventKitUI, targeting Swift 6.3 and iOS 26+. It spans authorization, event and reminder CRUD, recurrence rules, alarms, the EventKitUI editors, and observing store changes. Setup starts with Info.plist usage-description keys chosen by access level: NSCalendarsFullAccessUsageDescription for read and write, NSCalendarsWriteOnlyAccessUsageDescription for direct write-only creation, and NSRemindersFullAccessUsageDescription for reminders, plus legacy keys for iOS 10 through 16. A single EKEventStore instance is created and reused throughout, and objects from different stores are never mixed.

Authorization follows the granular iOS 17+ model: requestFullAccessToEvents for reading, editing, deleting, or fetching; requestWriteOnlyAccessToEvents for apps that only create events and never read them; and requestFullAccessToReminders for reminders. Only .fullAccess supports reads, and notably an app that merely presents EKEventEditViewController to let the person create an event needs no calendar authorization at all on iOS 17+.

Events are built as EKEvent objects and saved with a span such as .thisEvent, optionally targeting a specific writable calendar or attaching an EKStructuredLocation. Fetching uses date-range predicates that expand recurring occurrences, capped to a four-year span, and runs synchronously; reminders instead fetch asynchronously through a completion handler. Recurrence is expressed with EKRecurrenceRule, from simple frequency-and-interval rules with an optional EKRecurrenceEnd to complex rules using EKRecurrenceDayOfWeek and related components. The guide also includes alarms, EventKitUI controllers, change observation, and common-mistakes and review-checklist sections to steer correct usage.