swift – iOS Live Activities + multi-phase timers (Pomodoro / boxing rounds) without push notifications – is proper sync even possible?

iOS Live Activities + multi-phase timers (Pomodoro / boxing rounds) without push notifications – is proper sync even possible?

Hey everyone 👋

I’m building a Pomodoro timer and a boxing/round timer in SwiftUI and want them to work nicely with Live Activities (Lock Screen + Dynamic Island). Both have the same core idea: a timer with multiple phases (work/rest or round/break), and I’d like:

• a circular timer + countdown in the app,

• a Live Activity showing the current phase + countdown,

• and automatic phase changes (e.g. work → rest → work, or round → break → round) that stay in sync between the app and the Live Activity.

What I’ve tried:

• Classic endTime in ContentState and Text(endTime, style: .timer) in the widget → works for a single phase, but when the time is up and the app is suspended, the Live Activity hits 0:00 and just stays there (or starts counting up), because the app can’t call update(...) anymore.

• A pattern-based approach (store sessionStart, workDuration, restDuration and compute the phase based on Date() in the widget) → the Live Activity UI isn’t reliably recomputed every second, and you’re basically fighting ActivityKit’s design.

• Hybrid: app runs its own timer and calls update(...) on phase changes → works only while the app is alive. Once iOS suspends it in the background, no more updates → Live Activity stops changing phase.

Constraints:
I explicitly don’t want to use a backend or ActivityKit push updates – only local logic.

So my question:

👉 Is it actually possible, purely locally (no server, no push), to keep a multi-phase timer (work/rest, rounds/breaks) and a Live Activity truly in sync, including automatic phase transitions while the device is locked?

If you’ve shipped a timer/interval/workout app that does this without a backend, how are you handling phase changes and keeping the in-app timer + Live Activity in sync?

Right now my only “honest” solution seems to be: one Live Activity per current phase (just count down to 0:00) and then rely on a notification / user interaction to start the next phase. Curious if anyone has a better approach.