I’m working on a simple timer, similar to the native iOs one in the Clock App.

In my app the user can tap a button to launch the liveActivity which shows up on the lock screen displaying the name of the timer, the time running down via the Text timerInterval initializer and a button to pause it relying on LiveActivityIntent.

struct MyWidgetsLiveActivity: Widget {
    
    var body: some WidgetConfiguration {
        ActivityConfiguration(for: MyWidgetsAttributes.self) { context in
            // Lock screen/banner UI goes here
                HStack {
                    Text(context.attributes.name)
                        .font(.title2)
                        .bold()
                        .multilineTextAlignment(.leading)
                    Text(timerInterval: context.state.startedAt...Date(timeInterval: context.state.remainingTime, since: .now), pauseTime: context.state.timerRuns == false ? Date(timeInterval: context.state.remainingTime, since: .now) : nil, countsDown: true)
                        .multilineTextAlignment(.trailing)
                        .font(.largeTitle)
                    Text(String(context.state.timerRuns))
                    Button (intent: PauseTimer(id: context.attributes.name)) {
                        Image(systemName: "pause.circle.fill")
                    }
                    .buttonBorderShape(.circle)
                }
                .padding()
                .activityBackgroundTint(.white)
                .activitySystemActionForegroundColor(Color.black)
        } dynamicIsland: {....

However I can’t figure out a way to trigger an event once the countdown displayed in the Text-timerInterval hits zero, is there a way to do this?

Usually for an in-App-only timer I’d use the actual swift Timer and update a variable like remainingTime until that hits zero and read it to trigger the event like a sound in the code below, but I don’t know how to achieve the same using this Text-timerInterval.

Otherwise if this is impossible, should I rely on something like the below and feed it into the LiveActivity view having it update as each second goes by?

func startTimer() {
        timer?.invalidate()
        timer = nil
        timer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) {_ in
            if remainingTime > 0 {
                remainingTime -= 0.1
                timeProgress = remainingTime / TimeInterval(goal.totalSeconds)
                goal.remainingTime = remainingTime
            } else {
                timer?.invalidate()
                timer = nil
                SoundManager.instance.stopSound()
                SoundManager.instance.playSound(selectedSound: selectedSound.replacingOccurrences(of: " ", with: ""))
                goal.remainingTime = TimeInterval(goal.totalSeconds)
                do {
                    try modelContext.save()
                } catch {
                    fatalError("Couldn't save your timer.")
                }
            }
        }
    }