EmailValidation.swift

import Foundation

struct EmailAddress: RawRepresentable, Codable {
  let rawValue: String

  init?(rawValue: String) {
    let detector = try? NSDataDetector(types: NSTextCheckingResult.CheckingType.link.rawValue)
    let range = NSRange(rawValue.startIndex..<rawValue.endIndex,in: rawValue)
    let matches = detector?.matches(in: rawValue, options: [], range: range)
    guard let match = matches?.first, matches?.count == 1 else { return nil }
    guard match.url?.scheme == "mailto", match.range == range else { return nil }
    self.rawValue = rawValue
  }
}

Usage.swift

guard let email = EmailAddress(rawValue: "example@gmail.com") else {
  fatalError("not email address")
}
print(email)

guard let notEmail = EmailAddress.init(rawValue: "https://google.com") else {
  throw URLError(.badURL)
}