ios - iPad 上的键盘高度不正确

Question

我有一个 UIView 固定在我的 superview 的底部。它有一个 TextView ，点击后将成为第一响应者。此时，我检测到键盘将显示并更改其底部约束以将其向上移动，使其位于键盘上方。我使用以下代码来执行此操作:

private func keyboardWillShow(_ aNotification: Notification) {
    guard let info = (aNotification as NSNotification).userInfo,
        let endFrame = (info as NSDictionary).value(forKey: UIResponder.keyboardFrameEndUserInfoKey),
        let currentKeyboard = (endFrame as AnyObject).cgRectValue,
        let rate = info[UIResponder.keyboardAnimationDurationUserInfoKey] as? NSNumber
        else { return }

    let convertedFrame = self.view.convert(currentKeyboard, from: UIScreen.main.coordinateSpace)
    bottomConstraint.constant = self.view.frame.height - convertedFrame.origin.y

    UIView.animate(withDuration: rate.doubleValue) {
        self.view.layoutIfNeeded()
    }
}

这在 iPhone 上运行良好。然而，在 iPad 上，它似乎被移至应有高度的两倍。这是为什么？

Answer 1

转换键盘框架时，应将 nil 传递给 from 参数。这可以正确地从窗口坐标进行转换(如 UIView 转换文档中所述)。

如果您避免所有 Objective-C 编码，您的代码也会更简单。

private func keyboardWillShow(_ aNotification: Notification) {
    guard let info = aNotification.userInfo,
        let endFrame = info[UIWindow.keyboardFrameEndUserInfoKey] as? NSValue,
        let rate = info[UIWindow.keyboardAnimationDurationUserInfoKey] as? NSNumber
        else { return }

    let currentKeyboard = endFrame.cgRectValue
    let convertedFrame = self.view.convert(currentKeyboard, from: nil)
    bottomConstraint.constant = self.view.frame.height - convertedFrame.origin.y

    UIView.animate(withDuration: rate.doubleValue) {
        self.view.layoutIfNeeded()
    }
}