Implementing UITextFieldDelegate with Swift

Swift 3.0.1

 // UITextField Delegates
    func textFieldDidBeginEditing(_ textField: UITextField) {
    }
    func textFieldDidEndEditing(_ textField: UITextField) {
    }
    func textFieldShouldBeginEditing(_ textField: UITextField) -> Bool {
        return true;
    }
    func textFieldShouldClear(_ textField: UITextField) -> Bool {
        return true;
    }
    func textFieldShouldEndEditing(_ textField: UITextField) -> Bool {
        return true;
    }
    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        return true;
    }
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        textField.resignFirstResponder();
        return true;
    }

class ViewController: UIViewController,UITextFieldDelegate  //set delegate to class 

@IBOutlet var txtValue: UITextField             //create a textfile variable 

override func viewDidLoad() {
    super.viewDidLoad()
    txtValue.delegate = self                  //set delegate to textfile
}


func textFieldDidBeginEditing(textField: UITextField!) {    //delegate method

}

func textFieldShouldEndEditing(textField: UITextField!) -> Bool {  //delegate method
    return false
}

func textFieldShouldReturn(textField: UITextField!) -> Bool {   //delegate method
  textField.resignFirstResponder()

    return true
}