class TXApp extends Application.AppBase {
    var lastIsNetworkAvailable as Boolean = false;

    function isNetworkAvailable() as Boolean {
        var settings = System.getDeviceSettings();
        if (settings has :connectionAvailable) {
            return settings.connectionAvailable;
        }
        return settings.phoneConnected;
    }

    function checkNetworkAvailable() {
        var available = isNetworkAvailable();
        // network state changed
        if (lastIsNetworkAvailable != available) {
            setBackgroundEvent();
        }
        lastIsNetworkAvailable = available;
    }

    // called in both FG and BG
    function initialize() {
        AppBase.initialize();
        // ...
    }

    // only called in FG
    function getInitialView() {
        checkNetworkAvailable();
        setBackgroundEvent();
        // ...
    }

    function setBackgroundEvent() {
        if (Toybox.System has :ServiceDelegate) {
            var updatePeriod = Application.Properties.getValue("WU") as Number?;
            if (updatePeriod == null) {
                updatePeriod = 0; // or whatever the default setting value is
            }
            if (updatePeriod < 5) {
                // weather updates are disabled
                Background.deleteTemporalEvent();
                return;
            }
            // if network is not connected, use default of 5 minutes
            if (!lastIsNetworkAvailable) {
                updatePeriod = 5;
            }

            Background.registerForTemporalEvent(new Time.Duration(updatePeriod * 60));
        }
    }

    function onUpdate(dc as Dc) {
        checkNetworkAvailable();
        // ...
    }
    // ...
}