activitykit

activitykit helps implement, review, and improve Live Activities and Dynamic Island experiences in iOS apps using Apple's ActivityKit framework. Live Activities are real-time, glanceable displays on the Lock Screen and, on supported devices, the Dynamic Island, well suited to delivery tracking, sports scores, ride-sharing status, workout timers, and media playback. The skill keeps clear routing boundaries: ordinary Home Screen and timeline widgets belong to a widgetkit skill and generic APNs setup to push-notifications, while Live Activity-specific payload shapes stay in scope here.

It covers the full workflow for creating a Live Activity: adding NSSupportsLiveActivities to the host app's Info.plist, defining an ActivityAttributes struct with a nested ContentState, building an ActivityConfiguration with Lock Screen and Dynamic Island closures, starting the activity with Activity.request, updating with activity.update and ending with activity.end, and forwarding push tokens to a server for remote updates. Static attributes are set once at creation while the dynamic ContentState, kept deliberately small because it is serialized on every update, carries changing data. The skill explains staleDate and relevanceScore on ActivityContent, AlertConfiguration for visible update banners, and dismissal policies (.default, .immediate, and .after) that control how long an ended activity lingers.

For push-to-update, it documents the Live Activity payload invariants: apns-push-type of liveactivity, an apns-topic of <bundle-id>.push-type.liveactivity, and an aps.content-state that must decode into the app's actual ActivityAttributes.ContentState Codable shape, cautioning against assuming a particular encoding for Date or ClosedRange<Date> unless the Swift model and server contract agree. Patterns target iOS 26+ with Swift 6.3, with lifecycle examples requiring iOS 16.2+ and Lock Screen support from iOS 16.1+. Use it when building or reviewing any time-sensitive, real-time updating widget; it emphasizes ending activities on every terminal path and correctly distinguishing the active lifetime from post-end Lock Screen linger. A references file holds complete code patterns for payloads, concurrent activities, state observation, and testing.