We guide our users to perform specific actions within our service using a timer, similar to interval training. Even when the user enters the background, they should receive a TTS notification and the live activity screen should be updated upon timer completion. Additionally, the user should be able to transition to the next timer at a specific time, even if they don't perform an action (which also requires TTS and live activity updates). Currently, the only thing we can control is scheduling a notification in advance. To enable background TTS notifications and control of live activity, we are considering using background notifications. However, they are irregular and more unstable in battery optimization situations, so we're wondering if there's a way to implement the desired functionality on iOS.