public override bool ValidateProperty(TKEntityProperty property) { emptyField = false; incorrectFormat = false; NSString email = (NSString)property.ValueCandidate; if (email == null || email.Length == 0) { emptyField = true; return(false); } string emailRegex = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}"; NSPredicate predicate = NSPredicate.FromFormat("SELF MATCHES %@", (NSString)emailRegex); incorrectFormat = !predicate.EvaluateWithObject(email); if (incorrectFormat) { return(false); } return(true); }