What happens to an app in use when an update command is received?

If the device receives an update command while the app is running in the foreground, the device displays a message asking you to confirm the update, with the options Cancel and Update.
If you select Cancel, the update command is sent again at the next sync.
If you select Update, the app is closed and updated.
If the target app is not running in the foreground, it is updated automatically.