Widgets Code-along, part 3: Advancing timelines

URL Sessions

• the TimelineProvider API is built with completion handlers instead of return values, specifically to make doing asynchronous tasks, like network fetches, easy

• we can use normal URL sessions end even background session tasks.

• since the widget has no app delegate, there’s a new View modifier, introduced just for widgets, to handle background URL sessions: .onBackgroundURLSessionEvents(matching:_:)

Link

• use SwiftUI’s Link to make elements of the widget deep link into your app.

• Link behaves like Button, but instead of passing an action, we pass a destination URL which will be passed to the app on launch.

• to read the URL in your views, use the .onOpenURL(perform:) modifier

Widget bundles

• In order to create/support multiple widgets in the same extension, we need to define a WidgetBundle

• The WidgetBundle will be the new entry point of the extension

• The WidgetBundle declares all available widgets in its body (up to 5 widgets)

@main
struct EmojiRangerBundle: WidgetBundle {
    @WidgetBundleBuilder
    var body: some Widget {
        EmojiRangerWidget()
        LeaderboardWidget()
    }
}

Dynamic configuration

• if we don’t know all of the configuration options at build time, we can provide a dynamic list of options via an SiriKit Intent extension, the same way we would for other Intent-based features

• to create a SiriKit extension, go to File > New Target and choose Intents Extension.

• in our Intent editor we will set our Intent type to something custom (in the screenshot above we set it to Hero):

• if we look at the definition of our custom type, by default it has two properties: identifier and displayString:

• these properties are defined in our Intent extension:

class IntentHandler: INExtension, DynamicCharacterSelectionIntentHandling {
    
    func provideHeroOptionsCollection(for intent: DynamicCharacterSelectionIntent,
                                      with completion: @escaping (INObjectCollection<Hero>?, Error?) -> Void) {
        let characters: [Hero] = CharacterDetail.availableCharacters.map { character in
            let hero = Hero(identifier: character.name, display: character.name)
            
            return hero
        }
        
        let remoteCharacters: [Hero] = CharacterDetail.remoteCharacters.map { character in
            let hero = Hero(identifier: character.name, display: character.name)
            
            return hero
        }
        
        let collection = INObjectCollection(items: characters + remoteCharacters)
        
        completion(collection, nil)
    }
    
    override func handler(for intent: INIntent) -> Any {
        return self
    }
}

• lastly, we will need to update our IntentTimelineProvider to support our dynamic configuration