Swift method to check for a valid email address (uses Apples data detector instead of a regex)

String+Email.swift

extension String {
    func isValidEmail() -> Bool {
        guard !self.lowercaseString.hasPrefix("mailto:") else { return false }
        guard let emailDetector = try? NSDataDetector(types: NSTextCheckingType.Link.rawValue) else { return false }
        let matches = emailDetector.matchesInString(self, options: NSMatchingOptions.Anchored, range: NSRange(location: 0, length: self.characters.count))
        guard matches.count == 1 else { return false }
        return matches[0].URL?.scheme == "mailto"
    }
}