static async Task <IEnumerable <Placemark> > PlatformGetPlacemarksAsync(double latitude, double longitude)
        {
            Permissions.EnsureDeclared <Permissions.Maps>();
            if (string.IsNullOrWhiteSpace(Platform.MapServiceToken))
            {
                throw new ArgumentNullException(nameof(Platform.MapServiceToken));
            }
            var map = await Platform.GetMapServiceAsync(Platform.MapServiceToken);

            var request = map.CreateReverseGeocodeRequest(latitude, longitude);

            var list = new List <Placemark>();

            foreach (var address in await request.GetResponseAsync())
            {
                list.Add(new Placemark
                {
                    CountryCode     = address.CountryCode,
                    CountryName     = address.Country,
                    AdminArea       = address.State,
                    SubAdminArea    = address.County,
                    Locality        = address.City,
                    SubLocality     = address.District,
                    Thoroughfare    = address.Street,
                    SubThoroughfare = address.Building,
                    FeatureName     = address.Street,
                    Location        = new Location(latitude, longitude),
                    PostalCode      = address.PostalCode,
                });
            }
            return(list);
        }
        static async Task <IEnumerable <Location> > PlatformGetLocationsAsync(string address)
        {
            Permissions.EnsureDeclared <Permissions.Maps>();
            if (string.IsNullOrWhiteSpace(Platform.MapServiceToken))
            {
                throw new ArgumentNullException(nameof(Platform.MapServiceToken));
            }
            var map = await Platform.GetMapServiceAsync(Platform.MapServiceToken);

            var request = map.CreateGeocodeRequest(address);
            var list    = new List <Location>();

            foreach (var position in await request.GetResponseAsync())
            {
                list.Add(new Location(position.Latitude, position.Longitude));
            }
            return(list);
        }