How to set delegate of UITextField in separate class in Swift?

I'm trying to implement UITextFieldDelegate in separate class, but it didn't working:

class ViewController: UIViewController {

    @IBOutlet var TextField: UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()
        let restrictor = TextFieldRestrictController()
        TextField.delegate = restrictor
    }
}

class TextFieldRestrictController : NSObject, UITextFieldDelegate {

    public func textField(_ textField: UITextField,
                          shouldChangeCharactersIn range: NSRange,
                          replacementString string: String) -> Bool {
        let inverseSet = NSCharacterSet(
            charactersIn:"0123456789.").inverted

        let components = string.components(separatedBy: inverseSet)

        let filtered = components.joined(separator:"")
        return string == filtered
    }
}

But this is working:

class ViewController: UIViewController {

    @IBOutlet var TextField: UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()
        TextField.delegate = self
    }

    public func textField(_ textField: UITextField,
                          shouldChangeCharactersIn range: NSRange,
                          replacementString string: String) -> Bool {
        let inverseSet = NSCharacterSet(
            charactersIn:"0123456789.").inverted

        let components = string.components(separatedBy: inverseSet)

        let filtered = components.joined(separator:"")
        return string == filtered
    }
}

Is there something wrong?