keyboardFrameEndUserInfoKey 没有显示正确的值？答案

【问题标题】：keyboardFrameEndUserInfoKey not showing correct values?keyboardFrameEndUserInfoKey 没有显示正确的值？
【发布时间】：2018-10-16 14:59:10
【问题描述】：

我的视图底部有一个文本输入字段，我正在尝试对其进行上下动画以保持在键盘顶部。

func setupKeyboardObservers() {
    NotificationCenter.default.addObserver(self, selector: #selector(handleKeyboardWillChangeFrame), name: UIResponder.keyboardWillChangeFrameNotification, object: nil)

    NotificationCenter.default.addObserver(self, selector: #selector(handleKeyboardDidShow), name: UIResponder.keyboardDidShowNotification, object: nil)

    NotificationCenter.default.addObserver(self, selector: #selector(handleKeyboardWillChangeFrame), name: UIResponder.keyboardWillHideNotification, object: nil)
}

@objc func handleKeyboardWillChangeFrame(notification: NSNotification) {

    let keyboardFrame = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue
    let keyboardDuration = (notification.userInfo?[UIResponder.keyboardAnimationDurationUserInfoKey] as? Double)

    print(keyboardFrame)
    orderDetailView?.textInputViewBottomAnchor?.constant = -keyboardFrame!.height
    UIView.animate(withDuration: keyboardDuration!) {
        self.view.layoutIfNeeded()
    }
}

OrderDetailView 是视图控制器的视图。

textinputview 是动画的部分，当键盘第一次出现时它可以正常工作，但是当我发送消息并且键盘退出第一响应者时，或者如果我通过在键盘外部单击而退出firstresponder，它不会动画回来。

当我从keyboardFrameEndUserInfoKey 打印cgrect 值时，它返回与键盘存在时相同的帧值（而不是0）。

这似乎只有在我从视图中向下拖动键盘时才能正常工作。

感谢您的帮助。

【问题讨论】：

标签： ios swift uitextfield

【解决方案1】：

在您的情况下，当键盘隐藏时高度仍然非零，我认为这是您的问题。您需要将键盘框架转换为您的视图坐标系并据此设置约束。检查以下内容：

@objc private func onKeyboardChange(notification: NSNotification) {
    guard let info = notification.userInfo else { return }
    guard let value: NSValue = info[UIKeyboardFrameEndUserInfoKey] as? NSValue else { return }
    let newFrame = value.cgRectValue

    if let durationNumber = info[UIKeyboardAnimationDurationUserInfoKey] as? NSNumber, let keyboardCurveNumber = info[UIKeyboardAnimationCurveUserInfoKey] as? NSNumber {
        let duration = durationNumber.doubleValue
        let keyboardCurve = keyboardCurveNumber.uintValue
        UIView.animate(withDuration: duration, delay: 0, options: UIViewAnimationOptions(rawValue: keyboardCurve), animations: {
            self.updateFromKeyboardChangeToFrame(newFrame)
        }, completion: { _ in
            // After animation
        })
    } else {
        self.updateFromKeyboardChangeToFrame(newFrame)
    }
}

private func updateFromKeyboardChangeToFrame(_ keyboardFrame: CGRect) {
    let view: UIView! // Whatever view that uses bottom constraint
    let bottomConstraint: NSLayoutConstraint! // Your bottom constraint

    let constant = view.bounds.height-max(0, view.convert(keyboardFrame, from: nil).origin.y)
    bottomConstraint.constant = max(0, constant)
    view.layoutIfNeeded()
}

在你的情况下，你似乎使用

let view = self.view
let bottomConstraint = orderDetailView?.textInputViewBottomAnchor

这取决于您如何定义约束，但您似乎需要使用负值作为bottomConstraint.constant = -max(0, constant)。

【讨论】：