在 iOS 8 上获取键盘大小不适用于外部键盘

Question

现在一直在看几个 SO 帖子，但似乎没有一个对我有帮助。只想设置一个UITableViews 底部约束，以便键盘永远不会位于表格视图的顶部。在iOS 8中似乎不可能。使用普通软键盘时它可以工作，但是在模拟器中删除它或使用真正的硬件键盘时，它仍然认为有一个软键盘。

代码：

var currentKeyboardHeight:CGFloat = 0.0

override public func viewDidLoad() {
    super.viewDidLoad()

    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillShow:", name: UIKeyboardWillShowNotification, object: nil)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: "keyboardWillHide:", name: UIKeyboardWillHideNotification, object: nil)
}

deinit {
    NSNotificationCenter.defaultCenter().removeObserver(self)
}

func keyboardWillShow(notification: NSNotification) {
    if let userInfo = notification.userInfo {
        var keyboardRect = userInfo[UIKeyboardFrameEndUserInfoKey]!.CGRectValue()

        let windowRect = view.window!.convertRect(keyboardRect, fromWindow:nil)
        let viewRect = view.convertRect(windowRect, fromView:nil)

        let deltaHeight = viewRect.size.height - currentKeyboardHeight

        currentKeyboardHeight = viewRect.size.height
        tableViewBottomConstraint.constant = currentKeyboardHeight
        UIView.animateWithDuration(0.25, animations: { () -> Void in
            self.view.layoutIfNeeded()
        })

        println("show keyboard: \(currentKeyboardHeight)")
    }
}

func keyboardWillHide(notification: NSNotification) {
    if let userInfo = notification.userInfo {
        var keyboardRect = userInfo[UIKeyboardFrameEndUserInfoKey]!.CGRectValue()
        keyboardRect = self.view.convertRect(keyboardRect, fromView: nil)

        let deltaHeight = keyboardRect.size.height - currentKeyboardHeight
        currentKeyboardHeight = 0
        tableViewBottomConstraint.constant = currentKeyboardHeight

        UIView.animateWithDuration(0.25, animations: { () -> Void in
            self.view.layoutIfNeeded()
        })

        println("hideKeyboard \(currentKeyboardHeight)")

    }
}

当在最后一个 tableviewrow 中选择 uitextview 时，只会打印这个：

show keyboard: 260.0

这是错误的。如果然后你打开软键盘（cmd+shift+k）：

show keyboard: 260.0
show keyboard: 297.0
show keyboard: 297.0

这是正确的。然后关闭（cmd+shift+k）：

hideKeyboard 0.0
show keyboard: 260.0
hideKeyboard 0.0

这是正确的

更新 1：

根据对此答案 (https://stackoverflow.com/a/2893327/511299) 的评论，UIKeyboardWillShowNotification 在使用 accessoryView 时总是会触发。

func setupKeyboardButtons()
{
    let numberToolbar = UIToolbar(frame: CGRectMake(0,0,320,50))
    numberToolbar.barStyle = UIBarStyle.Default

    let button1 = UIBarButtonItem(title: CANCEL_TEXT, style: UIBarButtonItemStyle.Plain, target: self, action: "keyboardCancelButtonTapped:")
    let button2 = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.FlexibleSpace, target: nil, action: nil)
    let button3 = UIBarButtonItem(title: SAVE_TEXT, style: UIBarButtonItemStyle.Plain, target: self, action: "keyboardDoneButtonTapped:")

    button1.tintColor = UIColor.darkGrayColor()

    numberToolbar.items = [button1, button2, button3]

    numberToolbar.sizeToFit()
    commentTextView.inputAccessoryView = numberToolbar
}

Answer 1

您可以检测是否连接了外部键盘，并通过执行类似操作将键盘的高度设置为 0。

Objective-C 版本：

CGRect finalKeyboardFrame = [[info objectForKey:UIKeyboardFrameEndUserInfoKey] CGRectValue];
finalKeyboardFrame = [self convertRect:finalKeyboardFrame fromView:self.window];

NSLog(@"origin.y: %f", finalKeyboardFrame.origin.y);

根据是否连接外部键盘正确显示 y 坐标：

origin.y：258.000000（未连接）

origin.y：474.000000（已连接）