WidgetKit

Glanceable widgets on home screen, lock screen, StandBy, and Control Center. Widgets are not mini apps — they render a system-scheduled timeline of static SwiftUI snapshots in a memory-constrained extension. The deep API reference — extension setup, timeline providers, every family, configuration, interactive widgets, App Group data sharing, lock screen, StandBy, controls — lives in references/guide.md. This file is the decision and discipline layer: read it first, open the guide for specifics.

Dials

Set these explicitly at the start; they change what "correct" means.

1. CONFIGURATION — static (StaticConfiguration + TimelineProvider; no user options) · app-intent (AppIntentConfiguration + AppIntentTimelineProvider, iOS 17+; user picks parameters via a WidgetConfigurationIntent — see the appintents skill).
2. FAMILIES — declare the exact supportedFamilies you actually design and lay out: system{Small,Medium,Large,ExtraLarge} (home screen; ExtraLarge is iPad/Mac) · accessory{Circular,Rectangular,Inline} (lock screen, iOS 16+) · control (Control Center / Lock Screen / Action button via ControlWidget, iOS 18+).
3. UPDATE_STRATEGY — timeline (provider returns entries + .after/.atEnd reload policy; system budget applies) · reload (.never policy; main app/intent calls WidgetCenter.shared.reloadTimelines(ofKind:) when data changes) · push (.never policy + APNs WidgetPushHandler, iOS 18+, for server-driven updates without burning the local budget).

When to use

Building or reviewing any widget, lock-screen accessory, StandBy layout, Control Center control, timeline provider, or widget data-sharing code. If the surface is a Live Activity or Dynamic Island, use activitykit (it shares the WidgetKit bundle but is driven by ActivityKit, not timelines). If the work is the AppIntent itself — widget configuration parameters or the intent behind an interactive Button/Toggle/control — use appintents.

Core rules