/**
     * Get emails addresses for all contacts on the device.
     * Make sure the following line is added to AndroidManifest.xml
     * <uses-permission android:name="android.permission.READ_CONTACTS" />
     */
    public void getEmails(Context context) {
        try {
            List<List<String>> contactEmails = new UQI(context)
                    .getData(Contact.getAll(), Purpose.SOCIAL("recommend friends"))
                    .asList(Contact.EMAILS);
            // Do something with contact emails
            System.out.println("Contact emails: " + contactEmails);
        } catch (PSException e) {
            e.printStackTrace();
        }
    }

    /**
     * Get the current location.
     * Make sure the following line is added to AndroidManifest.xml
     * <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
     */
    public void getCurrentLocation(Context context) {
        try {
            LatLon latLon = new UQI(context)
                    .getData(Geolocation.asCurrent(Geolocation.LEVEL_CITY), Purpose.UTILITY("check weather"))
                    .getFirst(Geolocation.LAT_LON);
            // Do something with geolocation
            Log.d("Location", "" + latLon.getLatitude() + ", " + latLon.getLongitude());
        } catch (PSException e) {
            e.printStackTrace();
        }
    }

    private static final double CENTER_LATITUDE = 40;
    private static final double CENTER_LONGITUDE = -80;
    private static final double RADIUS = 20.0;

    /**
     * Monitor location updates and callback when in a circular area.
     * Make sure the following line is added to AndroidManifest.xml
     * <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
     */
    public void geofence(Context context) {
        new UQI(context)
                .getData(Geolocation.asUpdates(10*1000, Geolocation.LEVEL_EXACT), Purpose.GAME("notify user"))
                .setField("inRegion", GeolocationOperators.inCircle(Geolocation.LAT_LON, CENTER_LATITUDE, CENTER_LONGITUDE, RADIUS))
                .onChange("inRegion", new Callback<Boolean>() {
                    @Override
                    protected void onInput(Boolean inRegion) {
                        // Do something when enters/leaves region.
                        Log.d("Geofence", inRegion ? "entering" : "leaving");
                    }
                });
    }

    private static final String SERVER_PHONE_NUMBER = "123456789";
    private static final String AUTH_MESSAGE_PREFIX = "Your code is ";

    /**
     * Wait for SMS messages and read the auth code
     * Make sure the following line is added to AndroidManifest.xml
     * <uses-permission android:name="android.permission.RECEIVE_SMS" />
     */
    public void readAuthSMS(Context context) {
        new UQI(context).getData(Message.asIncomingSMS(), Purpose.UTILITY("two-factor authentication"))
                .filter(Message.TYPE, Message.TYPE_RECEIVED)
                .filter(Message.CONTACT, SERVER_PHONE_NUMBER)
                .filter(StringOperators.contains(Message.CONTENT, AUTH_MESSAGE_PREFIX))
                .ifPresent(Message.CONTENT, new Callback<String>() {
                    @Override
                    protected void onInput(String text) {
                        String authCode = text.substring(13);
                        // Do something with the auth code
                        Log.d("Auth code", authCode);
                    }
                });
    }

    /**
     * Get local images in media storage.
     * Make sure the following line is added to AndroidManifest.xml
     * <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
     */
    public void getLocalImages(Context context) {
        try {
            List<String> filePaths = new UQI(context)
                    .getData(Image.getFromStorage(), Purpose.UTILITY("read photos"))
                    .setField("filePath", ImageOperators.getFilepath(Image.IMAGE_DATA))
                    .asList("filePath");
            // Do something with the images
            Log.d("Image paths", "" + filePaths);
        } catch (PSException e) {
            e.printStackTrace();
        }
    }

    private static final long DURATION = 10 * 1000; // 10 seconds
    private static final long INTERVAL = 10 * 60 * 1000; // 10 minutes

    /**
     * Get microphone loudness periodically.
     * Make sure the following line is added to AndroidManifest.xml
     * <uses-permission android:name="android.permission.RECORD_AUDIO" />
     */
    public void getLoudnessPeriodically(Context context) {
        new UQI(context)
                .getData(Audio.recordPeriodic(DURATION, INTERVAL), Purpose.HEALTH("monitor sleep"))
                .setField("loudness", AudioOperators.calcLoudness(Audio.AUDIO_DATA))
                .forEach("loudness", new Callback<Double>() {
                    @Override
                    protected void onInput(Double loudness) {
                        // Do something with the loudness value.
                        Log.d("Loudness", "" + loudness + " dB.");
                    }
                });
    }