I am working on a live activity showing realtime NYC subway arrival countdowns at a station. As trains arrive I want to remove them from the live activity so that only inbound trains are displayed.
As I understand it this will require a broadcast push notification every time a train arrives, but this is incredibly inefficient (and will likely be throttled) as trains can arrive many times per minute at a busy station. MTA data includes approximately 90 minutes of train arrivals. Is there no way to create a live activity timeline the way widgets can update at planned intervals?
The only viable option I've found is keeping the entire app alive in the background to update the live activity when required by registering for background location updates, but this seems like an unfriendly solution.