Common helpers in Xamarin

distance-long-lat-degrees

// http://developer.xamarin.com/recipes/ios/content_controls/map_view/display_a_location/

        /// <summary>Converts miles to latitude degrees</summary>
        public static double MilesToLatitudeDegrees(double miles) {
            double earthRadius = 3960.0; // in miles
            double radiansToDegrees = 180.0 / Math.PI;
            return (miles / earthRadius) * radiansToDegrees;
        }

        /// <summary>Converts miles to longitudinal degrees at a specified latitude</summary>
        public static double MilesToLongitudeDegrees(double miles, double atLatitude) {
            double earthRadius = 3960.0; // in miles
            double degreesToRadians = Math.PI / 180.0;
            double radiansToDegrees = 180.0 / Math.PI;
            // derive the earth's radius at that point in latitude
            double radiusAtLatitude = earthRadius * Math.Cos(atLatitude * degreesToRadians);
            return (miles / radiusAtLatitude) * radiansToDegrees;
        }

        /// <summary>Converts kilometres to latitude degrees</summary>
        public static double KilometresToLatitudeDegrees(double kms) {
            double earthRadius = 6371.0; // in kms
            double radiansToDegrees = 180.0 / Math.PI;
            return (kms / earthRadius) * radiansToDegrees;
        }

        /// <summary>Converts kilometres to longitudinal degrees at a specified latitude</summary>
        public static double KilometresToLongitudeDegrees(double kms, double atLatitude) {
            double earthRadius = 6371.0; // in kms
            double degreesToRadians = Math.PI / 180.0;
            double radiansToDegrees = 180.0 / Math.PI;
            // derive the earth's radius at that point in latitude
            double radiusAtLatitude = earthRadius * Math.Cos(atLatitude * degreesToRadians);
            return (kms / radiusAtLatitude) * radiansToDegrees;
        }

gps-from-string

        public static void ParseGPS(string gpsLocation, out double latitude, out double longitude) {
            int commaPos = gpsLocation.IndexOf(',', 1);
            Double.TryParse(gpsLocation.Substring(0, commaPos), out latitude);
            Double.TryParse(gpsLocation.Substring(commaPos + 1, gpsLocation.Length - commaPos - 1), out longitude);
        }