Update Dynamic Island and Live Activity with Push Notification

Dynamic Island

With the launch of Live Activity in iOS 16 and the official support of Dynamic Island in iOS 16.1, we have been able to submit to the App Store for release. Recently, I encountered some problems in testing the background update of Live Activity, so I will record them here.

What is Dynamic Island and Live Activity

Live Activity and Dynamic Island actually exist as two forms of the same widget, and they are configured using ActivityConfiguration in ActivityKit. Dynamic Island content is displayed normally on iPhone 14 Pro and iPhone 14 Pro Max, which have Dynamic Island support, while it is displayed as Live Activity on all other models.

struct GroceryDeliveryApp: Widget {
    var body: some WidgetConfiguration {
        ActivityConfiguration(for: GroceryDeliveryAppAttributes.self) { context in
            return VStack(alignment: .leading) {
                HStack {
                    VStack(alignment: .center) {
                        Text(context.state.courierName + " is on the way!").font(.headline)
                        Text(Date(timeIntervalSince1970: context.state.deliveryTime).formatted(Date.ISO8601FormatStyle()))
                    }
                }
            }.padding(15)
        } dynamicIsland: { context in
            
            DynamicIsland {
              // UI for expanded state
            } compactLeading: {
              // UI for leading in compact state
            } compactTrailing: {
              // UI for trailing in compact state
            } minimal: {
              // UI for minimal state
            }
            .keylineTint(.cyan)
        }
    }
}

How to update Dynamic Island and Live Activity

Unlike the normal home widgets, Live Activity does not have a timeline provider to provide a regular update mechanism, it can only rely on the App to update it actively, or rely on Push notifications to update it.

If you want to use an App to actively update Live Activity, it requires the App to have any kind of background running mode to keep the App running continuously in the background, so that the content displayed on the Live Activity can be updated according to the running status, but this may not…