Enable background sessions.
To use background sessions, enable the Background Modes capability for your WatchKit extension, and then select the desired modes (see Figure 1). Each mode sets its respective keys in the extension’s
The background modes allow your app to run in the background during a corresponding session. In general, your app needs to start the session in the foreground. Also, while the session is running, Apple Watch dispays your app whenever the user raises their wrist.