I prefer use an extension for that. Besides, this url http://emailregex.com can help you to test if regex is correct. In fact, the site offers differents implementations for some programming languages. I share my implementation for Swift 3.
extension String {
func validateEmail() -> Bool {
let emailRegex = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,6}"
return NSPredicate(format: "SELF MATCHES %@", emailRegex).evaluate(with: self)
}
}