Improve input validation considering the input as a Type

Email.swift

import Foundation

struct Email {
    private var string: String

    init(_ string: String) throws {
        try Validations.email(string)
        self.string = string
    }

    func address() -> String {
        return string
    }
}

struct User {
    let name: String
    let email: Email
}

Validation.swift

import Foundation

enum EvaluateError: Error {
    case isEmpty
    case isNotValidEmailAddress
    case isNotValidEmailLength
}

struct Validations {
    private static let emailRegEx = "(?:[a-zA-Z0-9!#$%\\&‘*+/=?\\^_`{|}~-]+(?:\\.[a-zA-Z0-9!#$%\\&'*+/=?\\^_`{|}"
        + "~-]+)*|\"(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21\\x23-\\x5b\\x5d-\\"
        + "x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])*\")@(?:(?:[a-z0-9](?:[a-"
        + "z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?|\\[(?:(?:25[0-5"
        + "]|2[0-4][0-9]|[01]?[0-9][0-9]?)\\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-"
        + "9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\\x01-\\x08\\x0b\\x0c\\x0e-\\x1f\\x21"
        + "-\\x5a\\x53-\\x7f]|\\\\[\\x01-\\x09\\x0b\\x0c\\x0e-\\x7f])+)\\])"

    static func email(_ string: String) throws {
        if string.isEmpty == true {
            throw EvaluateError.isEmpty
        }

        if isValid(input: string,
                   regEx: emailRegEx,
                   predicateFormat: "SELF MATCHES[c] %@") == false {
            throw EvaluateError.isNotValidEmailAddress
        }

        if maxLength(emailAddress: string) == false {
            throw EvaluateError.isNotValidEmailLength
        }
    }

    // MARK: - Private

    private static func isValid(input: String, regEx: String, predicateFormat: String) -> Bool {
        return NSPredicate(format: predicateFormat, regEx).evaluate(with: input)
    }

    private static func maxLength(emailAddress: String) -> Bool {
        // 64 chars before domain and total 80. '@' key is part of the domain.
        guard emailAddress.count <= 80 else {
            return false
        }

        guard let domainKey = emailAddress.firstIndex(of: "@") else { return false }

        return emailAddress[..<domainKey].count <= 64
    }
}