将观察者添加到UITextfield。永远不会开火？

Question

Swift 4.0 iOS 11.x

添加了一些UITextfields，成为第一个响应者而不是这些观察者。但他们似乎永远不会开火？我在这里缺少什么？

@IBOutlet weak var nameTextField: UITextField!
@IBOutlet weak var hintTextField: UITextField!

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    listenToTextFields()
}

private func listenToTextFields() {
    let center = NotificationCenter.default
    let queue = OperationQueue.main
    namedObserver = center.addObserver(forName: NSNotification.Name.UITextViewTextDidChange, object: nameTextField, queue: queue) { (notification) in
        print("You edited \(self.nameTextField.text)")
    }
    hintObserver = center.addObserver(forName: NSNotification.Name.UITextViewTextDidChange, object: hintTextField, queue: queue) { (notification) in
        print("You edited \(self.hintTextField.text)")
    }
}

当我在nameTextField或hintTextField中输入文本时，没有任何内容打印到控制台。尝试使类成为UITextFieldDelegate，并确实设置了textfield委托，但仍然没有通知我的方式？

Answer 1

使用XCode UI尝试，而不是通过代码执行。见下图。

Answer 2

好的，通过使用不同的通知让它工作似乎;但肯定不会这样做。

private func listenToTextFields() {
    let center = NotificationCenter.default
    let queue = OperationQueue.main
    let alert2Monitor = NSNotification.Name.UITextFieldTextDidEndEditing
    namedObserver = center.addObserver(forName: alert2Monitor, object: nameTextField, queue: queue) { (notification) in
      self.setWayPoint.didSetVariable(image: nil, name: self.nameTextField.text, hint: self.hintTextField.text)
    }
    hintObserver = center.addObserver(forName: alert2Monitor, object: hintTextField, queue: queue) { (notification) in
      self.setWayPoint.didSetVariable(image: nil, name: self.nameTextField.text, hint: self.hintTextField.text)
    }
}