addSpotsMarkers() {
    let promises_array:Array<any> = [];
    let geocoder = new google.maps.Geocoder();
    this.spotsProvider.getSpots().subscribe((spots: Spot[]) => {
      this.spots = spots;
      this.spots.forEach((spot: Spot) => {
        promises_array.push(new Promise((resolve, reject) => {
          geocoder.geocode( { 'address': spot.address + ', ' + spot.city}, function(results, status) {
            console.log('results: ', results);
            console.log('status', status);
            if (status == google.maps.GeocoderStatus.OK) {
              resolve(results);

            } else {
              console.error(status);

            }
          });
        }));
      });
    });

    return Promise.all(promises_array);
}