// Readonly views
var borderView: UIView!
var bottomBorderView: UIView!
var placeholderLabel: UILabel!

// Border
var borderInactiveColor: UIColor = .lightGray
var borderActiveColor: UIColor = .red
var borderWidth: CGFloat = 2.0

// Placeholder
var placeholderFontScale: CGFloat = 0.7
var placeholderColor: UIColor = .black
var placeholder: String  // Setup placeholder inside Inteface Builder or right inside code!

// Error
var errorColor: UIColor = .red
var errorValidationHandler: (String) -> (String?)
var isValid: Bool  // (readonly) Anytime you could check textField validation status

emailTextField.errorValidationHandler = { text in
    let emailRegEx = "[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,}"

    let emailTest = NSPredicate(format:"SELF MATCHES %@", emailRegEx)
    let match = emailTest.evaluate(with: text)
    return (match ? "Invalid email" : nil)
}

open override func configureTextField(forTextFieldStateType textFieldStateType: BaseBeautifulTextField.TextFieldStateType, forTextStateType textStateType: BaseBeautifulTextField.TextStateType, animated: Bool, animations: (() -> ())?, completion: ((Bool) -> ())?) {
    super.configureTextField(forTextFieldStateType: textFieldStateType, forTextStateType: textStateType, animated: animated, animations: { 
        switch textFieldStateType {
        case .display:
            self.textColor = self.textColor?.withAlphaComponent(0.6)

        case .entry:
            self.textColor = self.textColor?.withAlphaComponent(1.0)
        }
    }) { (finished) in
        // ...
    }
}