iOS11-成为第一响应者而不是打开键盘

我正在使用swift 2.2 for iOS app.

我有一个UIButton,其中有一个.TouchUpInside触发UITextField成为的事件first responder.

以下是输入:

    self.manualInput = BrandTextField(y: 0, parentWidth: self.view.frame.width)
    self.manualInput.returnKeyType = .Search
    self.manualInput.autocorrectiOnType= .No

    self.manualInput.hidden = true
    self.manualInput.text = ""
    self.manualInput.delegate = self
    self.manualInput.autocapitalizatiOnType= .AllCharacters
    self.manualInput.moveX(0)
    self.manualInput.changeWidth(self.view.frame.width)
    self.manualInput.layer.cornerRadius = 0

    self.backgroundView.addSubview(self.manualInput)

下面是按钮:

self.keyboardButton = ActionButton(x: Dimensions.xScaleValue(170), y: Dimensions.yScaleValue(495), onTitle: "Enter code", offTitle: "Enter code", onImage: "manual_entry", offImage: "manual_entry", imageOn: true, action: {
    self.manualInput.becomeFirstResponder()
    print("Open the input")
})
self.backgroundView.addSubview(self.keyboardButton)

我也有这两个观察者:

NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(self.keyBoardWillShow), name: UIKeyboardDidShowNotification, object: nil)
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(self.keyBoardWillHide), name: UIKeyboardWillHideNotification, object: nil)


func keyBoardWillShow(notification: NSNotification) {
    print("Keyboard will show")
    let frame = (notification.userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue).CGRectValue()

    self.manualInput.moveY(frame.origin.y - self.manualInput.frame.height)
    self.manualInput.hidden = false
}

func keyBoardWillHide(notification: NSNotification) {
    print("Keyboard will hide")
    self.manualInput.moveY(0)
    self.manualInput.hidden = true
}

问题是,当我按下iOS 11时的按钮时,会触发becomeFirstResponder()行,但不会显示键盘.

对我来说,奇怪的是,如果我初始化视图中的输入并使其不隐藏按钮仍然不起作用.除非我点击输入,否则关闭键盘,然后使用按钮触发.

我不知道我是否在iOS 11的设置中遗漏了一些内容,或者我是否可以不再这样做了？