How to restore now playing app when it is unloaded and restarted with play button?

To restore a "Now Playing" app when it is unloaded and restarted with the play button, you can leverage the system's ability to manage app states and sessions. Here are some relevant insights from the WWDC sessions:

Session Lifecycle Management: According to the session on "What’s new in location authorization," when an app is terminated, the system can resume or relaunch the app into the background when new information is ready for delivery, provided the app's authorization allows it. This means that your app should be designed to recognize its previous state and resume its activities when relaunched. You can find more about this in the What’s new in location authorization session.
App Intents and State Management: In the session "Extend your app’s controls across the system," it is mentioned that you can use app intents to manage the state of your app. For example, if your app has a timer or a similar feature, you can use intents to toggle states and ensure that the app's state is updated across different devices. This can be particularly useful for maintaining the "Now Playing" state across app restarts. More details can be found in the Extend your app’s controls across the system session.

By implementing these strategies, you can ensure that your app can restore its "Now Playing" state effectively when it is restarted.