键盘向上时计算键盘尺寸并减小视图高度的问题

Question

我正在为练习创建扩展名，只需简单地调用它即可，它可以在键盘抬起时控制视图高度，并在将来使事情变得更容易。

这是屏幕截图： （我在控制器父视图中创建了一个scrollView，因此当键盘向上时，用户可以滚动整个页面）

问题：

1-键盘高度有时是错误的，具体取决于我如何连接scrollView底部约束。

2-有时应该给scrollView底部约束一个负值，以使scrollView变小，有时它需要一个正值！它也取决于您如何将scrollView底部约束与其superView连接起来（这就是我创建“ isReverse”变量的原因）。

这是我的扩展名：

extension UIViewController {

func watchKeyboard() {
    NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(self.keyboardWillHide), name: UIResponder.keyboardWillHideNotification, object: nil)
}

@objc private func keyboardWillShow(notification: NSNotification) {
    let isReverse = true // in some case you should turn this boolean to false to get the proper result.
    if tabBarController != nil {
        if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
            if let bottomConstraint = view.constraints.filter({ $0.firstAttribute == .bottom }).first {
                UIView.animate(withDuration: 0.4) {
                    if isReverse {
                        bottomConstraint.constant = -keyboardSize.height + self.tabBarController!.tabBar.frame.size.height
                    } else {
                        bottomConstraint.constant = keyboardSize.height - self.tabBarController!.tabBar.frame.size.height
                    }
                    self.view.layoutIfNeeded()
                }
            }
        }
    } else {
        if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameEndUserInfoKey] as? NSValue)?.cgRectValue {
            let isReverse = true // in some case you should turn this boolean to false to get the proper result.
            if let bottomConstraint = view.constraints.filter({ $0.firstAttribute == .bottom }).first {
                UIView.animate(withDuration: 0.4) {
                    bottomConstraint.constant = isReverse ? -keyboardSize.height : keyboardSize.height
                    self.view.layoutIfNeeded()
                }
            }
        }
    }
}

@objc private func keyboardWillHide(notification: NSNotification) {
    if let bottomConstraint = view.constraints.filter({ $0.firstAttribute == .bottom }).first {
        UIView.animate(withDuration: 0.4) {
            bottomConstraint.constant = 0
            self.view.layoutIfNeeded()
        }
    }
}
}

预先感谢...