Checks if a string contains a URL

containsUrlFunction.cs

        public static ValidationResult ContainsUrl(string sampleStr)
        {

            if(Uri.IsWellFormedUriString(sampleStr, UriKind.Absolute))
            {
                return new ValidationResult("Message Contains a URL.");
            }

            Regex urlRx = new Regex(@"(?<url>(http:[/][/]|www.)([a-z]|[A-Z]|[0-9]|[/.]|[~])*)", RegexOptions.IgnoreCase);
            MatchCollection matches = urlRx.Matches(sampleStr);

            if(matches.Count > 0)
            {
                return new ValidationResult("Message Contains a URL.");
            }
            return ValidationResult.Success;

        }