Activitykit

ActivityKit

ActivityKit owns real-time, glanceable Live Activities displayed on the Lock Screen and Dynamic Island. Ordinary timeline widgets belong in widgetkit, and generic APNs setup belongs in push-notifications; ActivityKit owns the Live Activity lifecycle and payload contract. aps.content-state must decode into the exact ActivityAttributes.ContentState shape, including any coordinated custom date/range encoding. Modern ActivityContent lifecycle examples require iOS 16.2+ unless noted.

See references/activitykit-patterns.md [blocked] for complete code patterns including push payload formats, concurrent activities, state observation, and testing.

Contents

• Workflow
• ActivityAttributes Definition
• Activity Lifecycle
• Lock Screen Presentation
• Dynamic Island
• Push-to-Update
• Recent Additions
• Common Mistakes
• Review Checklist
• References

Workflow

1. Create a new Live Activity

1. Verify the host app capability and NSSupportsLiveActivities = YES.
2. Define ActivityAttributes.ContentState; encode and decode a representative fixture that matches the server payload contract.
3. Create ActivityConfiguration and preview Lock Screen and Dynamic Island states, including stale and terminal content.
4. Check ActivityAuthorizationInfo.areActivitiesEnabled, then request and observe the activity lifecycle.
5. Exercise local update and every terminal end path.
6. For remote updates, validate a complete reference payload before registering rotating update or push-to-start tokens with the server.

2. Review existing Live Activity code

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

ActivityAttributes Definition

Define both static data (immutable for the activity lifetime) and dynamic ContentState (changes with each update). Keep ContentState small because the entire struct is serialized on every update and push payload.

import ActivityKit
struct DeliveryAttributes: ActivityAttributes {    // Static -- set once at activity creation, never changes    var orderNumber: Int    var restaurantName: String
    // Dynamic -- updated throughout the activity lifetime    struct ContentState: Codable, Hashable {        var driverName: String        var estimatedDeliveryTime: ClosedRange<Date>        var currentStep: DeliveryStep    }}
enum DeliveryStep: String, Codable, Hashable, CaseIterable {    case confirmed, preparing, pickedUp, delivering, delivered
    var icon: String {        switch self {        case .confirmed: "checkmark.circle"        case .preparing: "frying.pan"        case .pickedUp: "bag.fill"        case .delivering: "box.truck.fill"        case .delivered: "house.fill"        }    }}

Stale Date

Set staleDate on ActivityContent to tell the system when content becomes outdated. The system sets context.isStale to true after this date; show fallback UI (e.g., "Updating...") in your views.

let content = ActivityContent(    state: state,    staleDate: Date().addingTimeInterval(300), // stale after 5 minutes    relevanceScore: 75)

Activity Lifecycle

Starting

Use Activity.request to create and display a Live Activity. Pass .token as the pushType to enable remote updates via APNs. The ActivityContent request shown here requires iOS 16.2+.

let attributes = DeliveryAttributes(orderNumber: 42, restaurantName: "Pizza Place")let state = DeliveryAttributes.ContentState(    driverName: "Alex",    estimatedDeliveryTime: Date()...Date().addingTimeInterval(1800),    currentStep: .preparing)let content = ActivityContent(state: state, staleDate: nil, relevanceScore: 75)
do {    let activity = try Activity.request(        attributes: attributes,        content: content,        pushType: .token    )    print("Started activity: \(activity.id)")} catch {    print("Failed to start activity: \(error)")}

Updating

Update the dynamic content state from the app. Use AlertConfiguration to trigger a visible banner and sound alongside the update.

let updatedState = DeliveryAttributes.ContentState(    driverName: "Alex",    estimatedDeliveryTime: Date()...Date().addingTimeInterval(600),    currentStep: .delivering)let updatedContent = ActivityContent(    state: updatedState,    staleDate: Date().addingTimeInterval(300),    relevanceScore: 90)
// Silent updateawait activity.update(updatedContent)
// Update with an alertawait activity.update(updatedContent, alertConfiguration: AlertConfiguration(    title: "Order Update",    body: "Your driver is nearby!",    sound: .default))

Ending

End the activity when the tracked event completes. Choose a dismissal policy to control how long the ended activity lingers on the Lock Screen.

let finalState = DeliveryAttributes.ContentState(    driverName: "Alex",    estimatedDeliveryTime: Date()...Date(),    currentStep: .delivered)let finalContent = ActivityContent(state: finalState, staleDate: nil, relevanceScore: 0)
// System decides when to remove (up to 4 hours)await activity.end(finalContent, dismissalPolicy: .default)
// Remove immediatelyawait activity.end(finalContent, dismissalPolicy: .immediate)
// Remove after a specific time (max 4 hours from now)await activity.end(finalContent, dismissalPolicy: .after(Date().addingTimeInterval(3600)))

Always end activities on all terminal code paths -- success, user/app cancellation, sign-out/session stop, unrecoverable app error, and terminal server failure. If the server says the tracked event can no longer continue or be represented accurately, apply or send a final terminal state and end the activity instead of leaving stale progress visible. When reviewing duration claims, distinguish the active lifetime (up to 8 hours unless the app or user ends it sooner), system-ended Lock Screen presence (up to 4 additional hours, for 12 hours total from start), and app-ended .default dismissal linger (up to 4 hours after ending).

Lock Screen Presentation

The Lock Screen is the primary Live Activity display surface. Every device with iOS 16.1+ displays Live Activities here. Design this layout first, then adapt for Dynamic Island where available.

struct DeliveryActivityWidget: Widget {    var body: some WidgetConfiguration {        ActivityConfiguration(for: DeliveryAttributes.self) { context in            VStack(alignment: .leading) {                Text(context.attributes.restaurantName).font(.headline)
                if context.isStale {                    Label("Updating...", systemImage: "arrow.trianglehead.2.clockwise")                        .foregroundStyle(.secondary)                } else {                    Text(timerInterval: context.state.estimatedDeliveryTime, countsDown: true)                        .monospacedDigit()                }            }            .padding()        } dynamicIsland: { context in            DynamicIsland {                DynamicIslandExpandedRegion(.center) {                    Text(context.attributes.restaurantName).font(.headline)                }                DynamicIslandExpandedRegion(.trailing) {                    Text(timerInterval: context.state.estimatedDeliveryTime, countsDown: true)                }            } compactLeading: {                Image(systemName: "box.truck.fill")            } compactTrailing: {                Text(timerInterval: context.state.estimatedDeliveryTime, countsDown: true)            } minimal: {                Image(systemName: "box.truck.fill")            }        }    }}

Supplemental Activity Families

The Lock Screen presentation has limited vertical space. Avoid layouts taller than roughly 160 points. On iOS 18+, use supplementalActivityFamilies when you provide adaptive layouts beyond the default: .medium for iOS/macOS Live Activity sizing and .small for watchOS Live Activity sizing.

ActivityConfiguration(for: DeliveryAttributes.self) { context in    // Lock Screen content} dynamicIsland: { context in    // Dynamic Island}.supplementalActivityFamilies([.medium, .small])

Dynamic Island

Dynamic Island presentations appear only on devices that include Dynamic Island. Design all three modes, but treat the Lock Screen as the primary surface since not all devices have a Dynamic Island.

Compact (Leading + Trailing)

Used when one Live Activity occupies Dynamic Island compact space. Space is extremely limited -- show only the most critical information.

Minimal

Shown when multiple Live Activities compete for space. Only one activity gets the minimal slot. Display a single icon or glyph.

Expanded Regions

Shown when the user long-presses the Dynamic Island.

Keyline Tint

Apply a subtle tint to the Dynamic Island border:

DynamicIsland { /* expanded */ }    compactLeading: { /* ... */ }    compactTrailing: { /* ... */ }    minimal: { /* ... */ }    .keylineTint(.blue)

Push-to-Update

Push-to-update sends Live Activity updates through APNs, which is more efficient than polling from the app and works when the app is suspended, subject to APNs delivery, priority, budget, and throttling.

Setup

Pass .token as the pushType when starting the activity, then forward the per-activity update token to your server. Update tokens can rotate, so observe activity.pushTokenUpdates and re-register every emitted token:

let activity = try Activity.request(    attributes: attributes,    content: content,    pushType: .token)
// Observe token changes -- tokens can rotateTask {    for await token in activity.pushTokenUpdates {        let tokenString = token.map { String(format: "%02x", $0) }.joined()        try await ServerAPI.shared.registerActivityToken(            tokenString, activityID: activity.id        )    }}

APNs Payload Format

Send an HTTP/2 POST to APNs with these headers and JSON body:

Required device-token HTTP headers:

• apns-push-type: liveactivity
• apns-topic: <bundle-id>.push-type.liveactivity
• apns-priority: 5 (lower priority) or 10 (immediate, counts against budget)

The aps.alert payload controls visible alert/banner/sound behavior; priority alone does not create an alert.

Put timestamp, event, and the full content-state inside aps. Validate update, end, and push-to-start bodies against the complete examples in Push-to-Update Payloads [blocked], including the exact Codable date/range representation.

Push-to-Start

Start a Live Activity remotely without the app running (iOS 17.2+). Push-to-start tokens are ActivityKit-specific tokens from Activity<Attributes>.pushToStartTokenUpdates; they are distinct from ordinary app/device APNs tokens and per-activity update tokens:

Task {    for await token in Activity<DeliveryAttributes>.pushToStartTokenUpdates {        let tokenString = token.map { String(format: "%02x", $0) }.joined()        try await ServerAPI.shared.registerPushToStartToken(tokenString)    }}

Frequent Push Updates

Add NSSupportsLiveActivitiesFrequentUpdates = YES to Info.plist to increase the system-managed push update budget. When cadence matters, check ActivityAuthorizationInfo.frequentPushesEnabled and observe frequentPushEnablementUpdates; Apple does not guarantee a fixed update rate.

Recent Additions

Scheduled Live Activities (iOS 26+)

Schedule a Live Activity to start at a future time. The system starts the activity automatically without the app being in the foreground. Use for events with known start times (sports games, flights, scheduled deliveries).

let scheduledDate = Calendar.current.date(    from: DateComponents(year: 2026, month: 3, day: 15, hour: 19, minute: 0))!
let activity = try Activity.request(    attributes: attributes,    content: content,    pushType: .token,    style: .standard,    alertConfiguration: AlertConfiguration(        title: "Game Starting",        body: "The live score is ready.",        sound: .default    ),    start: scheduledDate)

ActivityStyle (iOS 18+ request parameter)

Use the iOS 18+ style: request parameter to choose persistence behavior. Use .standard for persistent Live Activities such as deliveries, rides, sports scores, timers, and flight/status boards. Use .transient only for a short-lived expanded Dynamic Island presentation; it can auto-end when the user locks the device, collapses or shrinks the expanded presentation, leaves the app, or does other work outside Dynamic Island.

let activity = try Activity.request(    attributes: attributes,    content: content,    pushType: .token,    style: .standard)

Paired Mac & CarPlay (iOS 26+)

Live Activities can appear on a paired Mac and on the CarPlay Home Screen. No additional ActivityKit API is required, but validate compact layouts; buttons and toggles in Live Activities do not perform actions in CarPlay.

Channel-Based Push (iOS 18+)

Broadcast updates to many Live Activities at once with an APNs-created channel ID. Enable the broadcast capability outside Xcode, create the channel on the server, then subscribe with .channel(channelID). Channel pushes update or end Live Activities; they do not start them. Use apns-channel-id and expiration for channel pushes instead of the device-token apns-topic example above.

let activity = try Activity.request(    attributes: attributes, content: content,    pushType: .channel(channelIDFromServer))

Common Mistakes

DON'T: Put too much content in the compact presentation -- it is tiny. DO: Show only the most critical info (icon + one value) in compact leading/trailing.

DON'T: Update Live Activities too frequently from the app (drains battery). DO: Use push-to-update for server-driven updates. Limit app-side updates to user actions.

DON'T: Forget to end the activity when the event reaches any terminal state. DO: End activities on success, cancellation, sign-out, unrecoverable errors, and terminal server failures. A leaked activity frustrates users.

DON'T: Assume every device has Dynamic Island. DO: Design for the Lock Screen as the primary surface; Dynamic Island is supplementary.

DON'T: Store sensitive information in ActivityAttributes (visible on Lock Screen). DO: Keep sensitive data in the app and show only safe-to-display summaries.

DON'T: Forget to handle stale dates. DO: Check context.isStale in views and show fallback UI ("Updating..." or similar).

DON'T: Ignore push token rotation. Tokens can change at any time. DO: Use activity.pushTokenUpdates async sequence and re-register on every emission.

DON'T: Forget the NSSupportsLiveActivities Info.plist key. DO: Add NSSupportsLiveActivities = YES to the host app's Info.plist (not the extension).

DON'T: Use the deprecated contentState-based API for request/update/end. DO: Use ActivityContent for all lifecycle calls.

DON'T: Fetch network data or location directly from Live Activity views. DO: Pre-compute display values in the app or server and pass them through ActivityKit updates or pushes.

Review Checklist

• ActivityAttributes defines static properties and ContentState
• NSSupportsLiveActivities = YES in host app Info.plist
• Activity uses ActivityContent (not deprecated contentState API)
• Activity ended in all terminal paths (success, error, cancellation, sign-out, terminal server failure)
• ActivityKit lifecycle and Lock Screen/Dynamic Island Live Activity surfaces are separated from ordinary Home Screen/timeline widget work
• Lock Screen layout, the primary Live Activity surface, handles context.isStale
• Dynamic Island compact, expanded, and minimal implemented with Lock Screen fallback
• Push update token forwarded to server via activity.pushTokenUpdates
• Push-to-start token collected via Activity<Attributes>.pushToStartTokenUpdates
• Push-to-start payload includes required alert
• content-state JSON matches the actual ContentState Codable shape, including coordinated date/range encoding
• Review distinguishes 8-hour active lifetime, 12-hour total system-ended Lock Screen presence, and 4-hour app-ended .default linger
• ActivityAuthorizationInfo checked before starting
• frequentPushesEnabled checked before assuming high-cadence pushes
• ContentState kept small (serialized on every update)
• iOS 18+ availability guarded for style:, .channel, and supplemental families
• iOS 18+ style: choices are justified: .standard for persistent Live Activities, .transient only for short-lived expanded Dynamic Island presentations
• ActivityKit push priority and aps.alert behavior are handled separately
• Live Activity views avoid direct network/location work
• Tested on device for push delivery and Dynamic Island behavior

References

• See references/activitykit-patterns.md [blocked] for patterns and code examples