出现键盘时调整 UITableView 的大小。动画是生涩的

Question

我有一个全屏 UITableView，它固定在顶部、底部、尾随和前导。此 ViewController 位于导航控制器内。我希望桌子的底部向上移动并在出现时使用键盘设置动画。我有以下代码：

    // MARK: Keyboard

    func registerObservers() {
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(_:)), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(_:)), name: NSNotification.Name.UIKeyboardWillHide, object: nil)
    }

    func unregisterObservers() {
        NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardWillShow, object: nil)
        NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardWillHide, object: nil)
    }

    func keyboardWillShow(_ notification: Notification) {
        let keyboardFrame = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as! NSValue).cgRectValue
        let keyboardAnimationDuration = notification.userInfo?[UIKeyboardAnimationDurationUserInfoKey] as! NSNumber
        let keyboardAnimationCurve = notification.userInfo?[UIKeyboardAnimationCurveUserInfoKey] as! NSNumber
        tableViewBottomConstraint.constant = keyboardFrame.height
        UIView.animate(withDuration: TimeInterval(keyboardAnimationDuration), delay: 0, options: [UIViewAnimationOptions(rawValue: UInt(keyboardAnimationCurve))], animations: {
            self.view.layoutIfNeeded()
        }, completion: { (finished: Bool) in
        })
    }

    func keyboardWillHide(_ notification: Notification) {
        let keyboardAnimationDuration = notification.userInfo?[UIKeyboardAnimationDurationUserInfoKey] as! NSNumber
        let keyboardAnimationCurve = notification.userInfo?[UIKeyboardAnimationCurveUserInfoKey] as! NSNumber
        tableViewBottomConstraint.constant = 0
        UIView.animate(withDuration: TimeInterval(keyboardAnimationDuration), delay: 0, options: [UIViewAnimationOptions(rawValue: UInt(keyboardAnimationCurve))], animations: {
            self.view.layoutIfNeeded()
        }, completion: { (finished: Bool) in
        })
    }

我在 ViewDidLoad 上注册了观察者。当键盘出现时，动画看起来很生涩。然而，解雇动画似乎没有任何问题。我在这里做错了什么？我是否设置了动画持续时间或曲线错误？

Answer 1

我通过执行以下操作来做到这一点：

为底部约束声明一个 IBOutlet 变量。请务必链接适当的约束，对于您的情况，这是 tableView 的底部约束。

@IBOutlet weak var bottomConstraint: NSLayoutConstraint!

添加一个函数来处理调整。

    func keyboardChangeFrame(_ notification: Notification) {
    let endFrame = ((notification as NSNotification).userInfo![UIKeyboardFrameEndUserInfoKey] as! NSValue).cgRectValue
    bottomConstraint.constant = view.bounds.height - endFrame.origin.y
    self.view.layoutIfNeeded()
}

最后，在 viewDidLoad 添加 UIKeyboardWillChangeFrame 观察者。

    NotificationCenter.default.addObserver(self
        , selector: #selector(keyboardChangeFrame)
        , name: NSNotification.Name.UIKeyboardWillChangeFrame
        , object: nil)