Setup
Authorization
Creating Events
Fetching Events
Reminders
Recurrence Rules
Alarms
EventKitUI Controllers
Observing Changes
Common Mistakes
Review Checklist
References

Setup

Info.plist Keys

Add the required usage description strings based on what access level you need:

Key	Access Level
`NSCalendarsFullAccessUsageDescription`	Read + write events
`NSCalendarsWriteOnlyAccessUsageDescription`	Write-only events (iOS 17+)
`NSRemindersFullAccessUsageDescription`	Read + write reminders

For apps also targeting iOS 16 or earlier, also include the legacy NSCalendarsUsageDescription / NSRemindersUsageDescription keys.

Event Store

Create a single EKEventStore instance and reuse it. Do not mix objects from different event stores.

import EventKit

let eventStore = EKEventStore()

Authorization

iOS 17+ introduced granular access levels. Use the modern async methods.

Full Access to Events

func requestCalendarAccess() async throws -> Bool {
    let granted = try await eventStore.requestFullAccessToEvents()
    return granted
}

Write-Only Access to Events

Use when your app only creates events (e.g., saving a booking) and does not need to read existing events.

func requestWriteAccess() async throws -> Bool {
    let granted = try await eventStore.requestWriteOnlyAccessToEvents()
    return granted
}

Full Access to Reminders

func requestRemindersAccess() async throws -> Bool {
    let granted = try await eventStore.requestFullAccessToReminders()
    return granted
}

Checking Authorization Status

let status = EKEventStore.authorizationStatus(for: .event)

switch status {
case .notDetermined:
    // Request access
    break
case .fullAccess:
    // Read and write allowed
    break
case .writeOnly:
    // Write-only access granted (iOS 17+)
    break
case .restricted:
    // Parental controls or MDM restriction
    break
case .denied:
    // User denied -- direct to Settings
    break
@unknown default:
    break
}

Creating Events

func createEvent(
    title: String,
    startDate: Date,
    endDate: Date,
    calendar: EKCalendar? = nil
) throws {
    let event = EKEvent(eventStore: eventStore)
    event.title = title
    event.startDate = startDate
    event.endDate = endDate
    event.calendar = calendar ?? eventStore.defaultCalendarForNewEvents

    try eventStore.save(event, span: .thisEvent)
}

Setting a Specific Calendar

// List writable calendars
let calendars = eventStore.calendars(for: .event)
    .filter { $0.allowsContentModifications }

// Use the first writable calendar, or the default
let targetCalendar = calendars.first ?? eventStore.defaultCalendarForNewEvents
event.calendar = targetCalendar

Adding Structured Location

import CoreLocation

let location = EKStructuredLocation(title: "Apple Park")
location.geoLocation = CLLocation(latitude: 37.3349, longitude: -122.0090)
event.structuredLocation = location

Fetching Events

Use a date-range predicate to query events. The events(matching:) method returns occurrences of recurring events expanded within the range.

func fetchEvents(from start: Date, to end: Date) -> [EKEvent] {
    let predicate = eventStore.predicateForEvents(
        withStart: start,
        end: end,
        calendars: nil  // nil = all calendars
    )
    return eventStore.events(matching: predicate)
        .sorted { $0.startDate < $1.startDate }
}

Fetching a Single Event by Identifier

if let event = eventStore.event(withIdentifier: savedEventID) {
    print(event.title ?? "No title")
}

Reminders

Creating a Reminder

func createReminder(title: String, dueDate: Date) throws {
    let reminder = EKReminder(eventStore: eventStore)
    reminder.title = title
    reminder.calendar = eventStore.defaultCalendarForNewReminders()

    let dueDateComponents = Calendar.current.dateComponents(
        [.year, .month, .day, .hour, .minute],
        from: dueDate
    )
    reminder.dueDateComponents = dueDateComponents

    try eventStore.save(reminder, commit: true)
}

Fetching Reminders

Reminder fetches are asynchronous and return through a completion handler.

func fetchIncompleteReminders() async -> [EKReminder] {
    let predicate = eventStore.predicateForIncompleteReminders(
        withDueDateStarting: nil,
        ending: nil,
        calendars: nil
    )

    return await withCheckedContinuation { continuation in
        eventStore.fetchReminders(matching: predicate) { reminders in
            continuation.resume(returning: reminders ?? [])
        }
    }
}

Completing a Reminder

func completeReminder(_ reminder: EKReminder) throws {
    reminder.isCompleted = true
    try eventStore.save(reminder, commit: true)
}

Recurrence Rules

Use EKRecurrenceRule to create repeating events or reminders.

Simple Recurrence

// Every week, indefinitely
let weeklyRule = EKRecurrenceRule(
    recurrenceWith: .weekly,
    interval: 1,
    end: nil
)
event.addRecurrenceRule(weeklyRule)

// Every 2 weeks, ending after 10 occurrences
let biweeklyRule = EKRecurrenceRule(
    recurrenceWith: .weekly,
    interval: 2,
    end: EKRecurrenceEnd(occurrenceCount: 10)
)

// Monthly, ending on a specific date
let monthlyRule = EKRecurrenceRule(
    recurrenceWith: .monthly,
    interval: 1,
    end: EKRecurrenceEnd(end: endDate)
)

Complex Recurrence

// Every Monday and Wednesday
let days = [
    EKRecurrenceDayOfWeek(.monday),
    EKRecurrenceDayOfWeek(.wednesday)
]

let complexRule = EKRecurrenceRule(
    recurrenceWith: .weekly,
    interval: 1,
    daysOfTheWeek: days,
    daysOfTheMonth: nil,
    monthsOfTheYear: nil,
    weeksOfTheYear: nil,
    daysOfTheYear: nil,
    setPositions: nil,
    end: nil
)
event.addRecurrenceRule(complexRule)

Editing Recurring Events

When saving changes to a recurring event, specify the span:

// Change only this occurrence
try eventStore.save(event, span: .thisEvent)

// Change this and all future occurrences
try eventStore.save(event, span: .futureEvents)

Alarms

Attach alarms to events or reminders to trigger notifications.

// 15 minutes before
let alarm = EKAlarm(relativeOffset: -15 * 60)
event.addAlarm(alarm)

// At an absolute date
let absoluteAlarm = EKAlarm(absoluteDate: alertDate)
event.addAlarm(absoluteAlarm)

EventKitUI Controllers

EKEventEditViewController — Create/Edit Events

Present the system event editor for creating or editing events.

import EventKitUI

class EventEditorCoordinator: NSObject, EKEventEditViewDelegate {
    let eventStore = EKEventStore()

    func presentEditor(from viewController: UIViewController) {
        let editor = EKEventEditViewController()
        editor.eventStore = eventStore
        editor.editViewDelegate = self
        viewController.present(editor, animated: true)
    }

    func eventEditViewController(
        _ controller: EKEventEditViewController,
        didCompleteWith action: EKEventEditViewAction
    ) {
        switch action {
        case .saved:
            // Event saved
            break
        case .canceled:
            break
        case .deleted:
            break
        @unknown default:
            break
        }
        controller.dismiss(animated: true)
    }
}

EKEventViewController — View an Event

import EventKitUI

let viewer = EKEventViewController()
viewer.event = existingEvent
viewer.allowsEditing = true
navigationController?.pushViewController(viewer, animated: true)

EKCalendarChooser — Select Calendars

let chooser = EKCalendarChooser(
    selectionStyle: .multiple,
    displayStyle: .allCalendars,
    entityType: .event,
    eventStore: eventStore
)
chooser.showsDoneButton = true
chooser.showsCancelButton = true
chooser.delegate = self
present(UINavigationController(rootViewController: chooser), animated: true)

Observing Changes

Register for EKEventStoreChanged notifications to keep your UI in sync when events are modified outside your app (e.g., by the Calendar app or a sync).

NotificationCenter.default.addObserver(
    forName: .EKEventStoreChanged,
    object: eventStore,
    queue: .main
) { [weak self] _ in
    self?.refreshEvents()
}

Always re-fetch events after receiving this notification. Previously fetched EKEvent objects may be stale.

Common Mistakes

DON'T: Use the deprecated requestAccess(to:) method

// WRONG: Deprecated in iOS 17
eventStore.requestAccess(to: .event) { granted, error in }

// CORRECT: Use the granular async methods
let granted = try await eventStore.requestFullAccessToEvents()

DON'T: Save events to a read-only calendar

// WRONG: No check -- will throw if calendar is read-only
event.calendar = someCalendar
try eventStore.save(event, span: .thisEvent)

// CORRECT: Verify the calendar allows modifications
guard someCalendar.allowsContentModifications else {
    event.calendar = eventStore.defaultCalendarForNewEvents
    return
}
event.calendar = someCalendar
try eventStore.save(event, span: .thisEvent)

DON'T: Ignore timezone when creating events

// WRONG: Event appears at wrong time for traveling users
event.startDate = Date()
event.endDate = Date().addingTimeInterval(3600)

// CORRECT: Set the timezone explicitly for location-specific events
event.timeZone = TimeZone(identifier: "America/New_York")
event.startDate = startDate
event.endDate = endDate

DON'T: Forget to commit batched saves

// WRONG: Changes never persisted
try eventStore.save(event1, span: .thisEvent, commit: false)
try eventStore.save(event2, span: .thisEvent, commit: false)
// Missing commit!

// CORRECT: Commit after batching
try eventStore.save(event1, span: .thisEvent, commit: false)
try eventStore.save(event2, span: .thisEvent, commit: false)
try eventStore.commit()

DON'T: Mix EKObjects from different event stores

// WRONG: Event fetched from storeA, saved to storeB
let event = storeA.event(withIdentifier: id)!
try storeB.save(event, span: .thisEvent) // Undefined behavior

// CORRECT: Use the same store throughout
let event = eventStore.event(withIdentifier: id)!
try eventStore.save(event, span: .thisEvent)

Review Checklist

References

Extended patterns (SwiftUI wrappers, predicate queries, batch operations): references/eventkit-patterns.md
EventKit framework
EKEventStore
EKEvent
EKReminder
EKRecurrenceRule
EKCalendar
EventKit UI
EKEventEditViewController
EKCalendarChooser
Accessing the event store
Creating a recurring event

eventkit-calendar

EventKit — Calendar & Reminders

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