UrlHelper class to validate URL

UrlHelper.cs

using System.Text.RegularExpressions;
using Umbraco.Extensions;

namespace Concept.Core.Helpers
{
    public static class UrlHelper
    {
        private const string URL_SCHEME_PATTERN = @"^(http:\/\/www\.|https:\/\/www\.|http:\/\/|https:\/\/)?[a-z0-9]+([\-\.]{1}[a-z0-9]+)*\.[a-z]{2,5}(:[0-9]{1,5})?(\/.*)?$";
        private const string URL_RELATIVE_PATTERN = @"^\/([\w-]+.)+[\w-]+(\/[\w- ])?\S$";

        public static string GetCorrectUrl(string url)
        {
            try
            {
                string sanitisedUrl = SanitiseUrl(url);

                if (IsValidUrl(sanitisedUrl)) return sanitisedUrl;

                return "#";
            }
            catch
            {
                return "#";
            }
        }

        public static bool IsValidUrl(string url)
        {
            try
            {
                Uri uriResult;
                Uri.TryCreate(url, UriKind.RelativeOrAbsolute, out uriResult);

                if (uriResult is null) return false;

                if (uriResult.IsAbsoluteUri) return true;

                if (Regex.IsMatch(uriResult.OriginalString, URL_SCHEME_PATTERN)) return true;

                if (Regex.IsMatch(uriResult.OriginalString, URL_RELATIVE_PATTERN)) return true;

                return false;
            }
            catch
            {
                return false;
            }
        }

        public static string SanitiseUrl(string url)
        {
            if (string.IsNullOrWhiteSpace(url)) return "#";

            if (url.StartsWith("http:") || url.StartsWith("https:") || url.StartsWith("mailto:") || url.StartsWith("tel:"))
            {
                return url;
            }

            if (url.StartsWith("//"))
            {
                return $"http:{url}";
            }

            if (url.StartsWith("www."))
            {
                return $"http://{url}";
            }

            if (Regex.IsMatch(url.ReplaceFirst("/", ""), URL_SCHEME_PATTERN))
            {
                return $"http://{url.ReplaceFirst("/", "")}";
            }

            if (!url.StartsWith("/"))
            {
                url = $"/{url}";
            }

            if (Regex.IsMatch(url, URL_RELATIVE_PATTERN))
            {
                return url;
            }

            return "#";
        }
    }
}