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alarmkit

Implement alarm and countdown timer features using Apple's AlarmKit framework (iOS 26+ / iPadOS 26+). Covers AlarmManager for scheduling alarms and timers, AlarmAttributes and AlarmPresentation for Lock Screen and Dynamic Island UI, AlarmButton for stop/snooze actions, authorization flows, alarm state observation, and Live Activity integration. Use when building wake-up alarms, countdown timers with system UI, or alarm-style notifications that surface on the Lock Screen and Dynamic Island.

personAuthor: jakexiaohubgithub
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AlarmKit

Schedule prominent alarms and countdown timers that surface on the Lock Screen, Dynamic Island, StandBy, and a paired Apple Watch when the alarm fires. AlarmKit requires iOS 26+ / iPadOS 26+. Alarms can break through Focus and Silent mode.

AlarmKit uses ActivityKit data models for its Live Activity, but the firing alert is system-managed alarm UI, not a general custom notification UI surface. Custom UI belongs only to countdown and paused Live Activity states rendered by a Widget Extension with the same AlarmAttributes<Metadata> and AlarmPresentationState used when scheduling.

See references/alarmkit-patterns.md for complete code patterns including authorization, scheduling, countdown timers, snooze handling, and widget setup.

import AlarmKit

Contents

Workflow

1. Create a new alarm or timer

  1. Add NSAlarmKitUsageDescription to Info.plist with a user-facing string.
  2. Request authorization with AlarmManager.shared.requestAuthorization() when the app can explain the value, or handle the first-schedule system prompt.
  3. If authorization is .denied or not .authorized, show recovery UI instead of scheduling.
  4. Configure AlarmPresentation (alert, countdown, paused states).
  5. Create AlarmAttributes with the presentation, optional metadata, and tint color.
  6. Build an AlarmManager.AlarmConfiguration (.alarm or .timer).
  7. Schedule with AlarmManager.shared.schedule(id:configuration:).
  8. Observe alarmManager.alarmUpdates and confirm the scheduled ID reaches the expected state.
  9. If using countdown, add a Widget Extension target with an ActivityConfiguration for the same AlarmAttributes<Metadata> type.

2. Review existing alarm code

Run through the Review Checklist at the end of this document.

Authorization

AlarmKit requires user authorization. Request early when the app can explain the value, or let AlarmKit prompt automatically on first schedule. If authorization is not granted after the explicit or automatic prompt, alarms are not scheduled and will not alert.

let manager = AlarmManager.shared

// Request authorization explicitly
let state = try await manager.requestAuthorization()
guard state == .authorized else { return }

// Check current state synchronously
let current = manager.authorizationState // .authorized, .denied, .notDetermined

// Observe authorization changes
for await state in manager.authorizationUpdates {
    switch state {
    case .authorized: print("Alarms enabled")
    case .denied:     print("Alarms disabled")
    case .notDetermined: break
    @unknown default: break
    }
}

Alarm vs Timer Decision

| Feature | Alarm (.alarm) | Timer (.timer) | |---|---|---| | Fires at | Specific time (schedule) | After duration elapses | | Countdown UI | Optional | Always shown | | Recurring | Yes (weekly days) | No | | Use case | Wake-up, scheduled reminders | Cooking, workout intervals |

Use .alarm(schedule:...) when firing at a clock time. Use .timer(duration:...) when firing after a duration from now.

Scheduling Alarms

Alarm.Schedule

Use .fixed(date) for a one-time absolute date or .relative for a local clock time with .never or .weekly repetition. Load Recurring Alarm Patterns for daily, weekday, weekend, and fixed-date variants.

Schedule and Configure

let id = UUID()

let alert = AlarmPresentation.Alert(
    title: "Wake Up",
    secondaryButton: AlarmButton(
        text: "Snooze", textColor: .white, systemImageName: "bell.slash"
    ),
    secondaryButtonBehavior: .countdown
)
let presentation = AlarmPresentation(alert: alert)
struct EmptyAlarmMetadata: AlarmMetadata {}
let attributes = AlarmAttributes<EmptyAlarmMetadata>(
    presentation: presentation,
    metadata: nil,
    tintColor: .indigo
)

let snooze = Alarm.CountdownDuration(preAlert: nil, postAlert: 300)
let configuration = AlarmManager.AlarmConfiguration(
    countdownDuration: snooze,
    schedule: .relative(.init(
        time: .init(hour: 7, minute: 0),
        repeats: .never
    )),
    attributes: attributes,
    sound: .default
)

let alarm = try await AlarmManager.shared.schedule(
    id: id,
    configuration: configuration
)

For an authorization-gated function and metadata-bearing variant, load Complete Alarm Scheduling Flow.

stopIntent and secondaryIntent default to nil. Omit stopIntent for AlarmKit's standard system Stop behavior; provide it only when Stop must run app cleanup, custom stop behavior, or other side effects. Omit secondaryIntent for ordinary Snooze/Repeat with secondaryButtonBehavior: .countdown and Alarm.CountdownDuration.postAlert; provide it only for .custom secondary behavior or app cleanup/custom behavior.

Alarm State Transitions

cancel(id:)
    |
scheduled --> countdown --> alerting
    |             |             |
    |         pause(id:)    stop(id:) / countdown(id:)
    |             |
    |         paused ----> countdown (via resume(id:))
    |
cancel(id:) removes from system entirely
  • cancel(id:) -- remove the alarm completely, including repeating alarms
  • pause(id:) -- pause a counting-down alarm; throws from other states
  • resume(id:) -- resume a paused alarm; throws from other states
  • stop(id:) -- stop the alarm; one-shot alarms are removed, repeating alarms reschedule
  • countdown(id:) -- restart countdown from alerting state (snooze); throws from other states

Countdown Timers

Timers fire after a duration and always show a countdown UI. Use Alarm.CountdownDuration to control pre-alert and post-alert durations.

CountdownDuration

Alarm.CountdownDuration controls the visible countdown phases:

  • preAlert -- seconds to count down before the alarm fires (the main countdown)
  • postAlert -- seconds for a repeat/snooze countdown after the alarm fires

Load Complete Countdown Timer Flow for the timer factory, pause/resume presentation, metadata, and scheduling gate.

Alarm States

Each Alarm has a state property reflecting its current lifecycle position.

| State | Meaning | |---|---| | .scheduled | Scheduled and ready to alert at the appropriate time | | .countdown | Actively counting down (timer or pre-alert phase) | | .paused | Countdown paused by user or app | | .alerting | Alarm is firing -- sound playing, UI prominent |

Observing State Changes

AlarmManager.shared.alarms is a throwing getter for the current daemon snapshot. Use try, and either propagate the error or wrap launch refresh in do/catch before relying on the snapshot.

Observe alarmUpdates rather than maintaining an independent lifecycle. Load State Observation with Async Sequences for the complete store and refresh loop.

An alarm that disappears from alarmUpdates is no longer scheduled with AlarmKit. Compare against app-persisted IDs when you need to distinguish fired, cancelled, and rescheduled alarms.

AlarmAttributes and AlarmPresentation

AlarmAttributes conforms to ActivityAttributes and defines the static data for the alarm's Live Activity. It is generic over a Metadata type conforming to AlarmMetadata, which inherits Decodable, Encodable, Hashable, and Sendable. The metadata value itself is optional and defaults to nil.

AlarmPresentation supplies the required alerting content and optional countdown/paused content. The system renders alerting UI; a widget extension can customize countdown and paused Live Activity views with the same attributes and presentation state. Keep metadata lightweight, use nil when it is unnecessary, and share its type with the widget extension.

AlarmPresentationState

AlarmPresentationState is the system-managed ContentState of the alarm Live Activity. It contains the alarm ID and a Mode enum:

  • .alert(Alert) -- alarm is firing, includes the scheduled time
  • .countdown(Countdown) -- actively counting down, includes fire date and durations
  • .paused(Paused) -- countdown paused, includes elapsed and total durations

The widget extension reads AlarmPresentationState.mode to decide which UI to render in the Dynamic Island and Lock Screen for non-alerting states.

AlarmButton

AlarmButton defines the text, color, and symbol for an alarm action. The representative scheduling example above shows a standard Snooze button.

Secondary Button Behavior

The secondary button on the alert UI has two behaviors:

| Behavior | Effect | |---|---| | .countdown | Restarts a countdown using postAlert duration (snooze) | | .custom | Triggers the secondaryIntent (e.g., open app) |

Live Activity Integration

AlarmKit alarms appear as Live Activities on the Lock Screen, Dynamic Island, StandBy, and on a paired Apple Watch when the alarm fires. The system manages the alerting UI. For countdown and paused states, add a Widget Extension target whose ActivityConfiguration uses the same AlarmAttributes<Metadata> type used when scheduling the alarm.

A widget extension is expected if your alarm uses countdown presentation. Keep that lightweight metadata type available to both the app and widget extension. Without the extension, alarms may be dismissed unexpectedly or fail to alert, though the system can still show a fallback countdown UI in limited cases such as after a device restart before first unlock.

| Work | Owner | |---|---| | Authorization, scheduling/state, presentation, sound, system alarm actions | AlarmKit | | Home Screen/Smart Stack widgets, families, timelines, reloads | widgetkit | | Non-alarm Live Activity lifecycle, tokens, remote content state | activitykit | | APNs, notification categories/actions, custom notification UI | push-notifications |

AlarmKit's alert is system-rendered on Lock Screen, Dynamic Island, StandBy, and paired Apple Watch; only countdown/paused states use the widget extension.

For setup, name Apple-documented NSAlarmKitUsageDescription and AlarmManager authorization. Do not require unsupported AlarmKit setup keys or com.apple.developer.alarmkit unless a current Apple source documents them. Load Live Activity Widget Extension for Alarms for the complete shared-attributes widget implementation.

Common Mistakes

| Mistake | Correction | |---|---| | Missing usage string or authorization gate | Add NSAlarmKitUsageDescription; handle denial before scheduling | | Timer used for recurrence | Use an alarm with .weekly([...]) | | App-owned state replaces alarmUpdates | Observe the system sequence and reconcile by ID | | Intents added for standard Stop/Snooze | Omit them unless cleanup/custom behavior requires one | | Large AlarmMetadata payload | Keep lightweight metadata or reference app data by ID | | Deprecated stopButton initializer | Use init(title:secondaryButton:secondaryButtonBehavior:) |

Review Checklist

  • [ ] Setup and authorization gates pass without unsupported entitlement keys
  • [ ] Alarm/timer choice, presentation, metadata, intents, snooze duration, and tint are valid
  • [ ] Scheduled IDs are retained and reconciled through alarmUpdates; operation errors are handled
  • [ ] Countdown uses the shared Widget Extension attributes and presentation state
  • [ ] System-managed alert UI and adjacent-skill ownership follow the routing table
  • [ ] Sound, vibration, Stop/Snooze, and state changes pass on-device testing

References