| name | widgets |
| description | WidgetKit: timeline provider, widget views, families, AppGroup data sharing, mandatory files. Use when implementing Apple extensions related to widgets. |
Widgets
WIDGETS (WidgetKit):
FRAMEWORK: import WidgetKit
SETUP:
- Requires separate widget extension target (kind: "widget" in plan extensions array)
- Use AppGroup for data sharing between app and widget (auto-configured in project.yml)
- Widget code goes in Targets/{WidgetName}/ directory
TIMELINE ENTRY (data for a single widget render):
struct MyEntry: TimelineEntry {
let date: Date
let title: String
let value: Double
}
TIMELINE PROVIDER (supplies entries to the system):
struct MyProvider: TimelineProvider {
func placeholder(in context: Context) -> MyEntry {
MyEntry(date: .now, title: "Placeholder", value: 0)
}
func getSnapshot(in context: Context, completion: @escaping (MyEntry) -> Void) {
completion(MyEntry(date: .now, title: "Snapshot", value: 42))
}
func getTimeline(in context: Context, completion: @escaping (Timeline) -> Void) {
let entry = MyEntry(date: .now, title: "Current", value: 42)
let timeline = Timeline(entries: [entry], policy: .after(.now.addingTimeInterval(3600)))
completion(timeline)
}
}
WIDGET VIEW:
struct MyWidgetView: View {
var entry: MyProvider.Entry
@Environment(.widgetFamily) var family
var body: some View {
switch family {
case .systemSmall:
VStack { Text(entry.title).font(AppTheme.Fonts.headline); Text("(Int(entry.value))").font(AppTheme.Fonts.largeTitle) }
case .systemMedium:
HStack { VStack(alignment: .leading) { Text(entry.title); Text("(Int(entry.value))").font(AppTheme.Fonts.title) }; Spacer() }
default:
Text(entry.title)
}
}
}
WIDGET DEFINITION:
struct MyWidget: Widget {
let kind: String = "MyWidget"
var body: some WidgetConfiguration {
StaticConfiguration(kind: kind, provider: MyProvider()) { entry in
MyWidgetView(entry: entry)
.containerBackground(.fill.tertiary, for: .widget) // REQUIRED iOS 17+
}
.configurationDisplayName("My Widget")
.description("Shows current status")
.supportedFamilies([.systemSmall, .systemMedium])
}
}
WIDGET BUNDLE (when multiple widgets exist):
@main
struct MyWidgetBundle: WidgetBundle {
var body: some Widget {
MyWidget()
AnotherWidget()
}
}
MANDATORY FILES (every widget extension MUST have ALL of these):
- {Name}Bundle.swift — @main WidgetBundle entry point. Without this, the extension has no entry point → linker error "undefined symbol: _main" → CodeSign failure.
- Provider.swift — TimelineProvider implementation.
- WidgetView.swift — The widget's SwiftUI view.
- (Optional) Intent.swift — AppIntent for interactive widgets (tap-to-complete, etc.).
CRITICAL RULES:
- .containerBackground(.fill.tertiary, for: .widget) is REQUIRED on the widget view in iOS 17+. Without it, the widget renders with no background.
- The @main entry point is MANDATORY. Use @main on WidgetBundle (multiple widgets) or Widget (single widget). An extension target with NO @main will fail to link.
- Shared data types between app and widget go in the Shared/ directory at the project root (both targets compile it). NEVER define shared types only in the main app's Models/ — the widget extension cannot see them.
- Widget views must be self-contained — they cannot use @StateObject, @ObservedObject, or network calls. All data comes through the TimelineEntry.
- Use .supportedFamilies() to declare which sizes the widget supports.
- AppIntent static properties MUST use "static let" (not "static var") for Swift 6 concurrency safety. Using "static var" causes "not concurrency-safe because it is nonisolated global shared mutable state" error.
