您可以通过订阅UIKeyboardWillShowNotification通知获得键盘高度。 (假设你想知道在显示之前会有什么高度)。

这样的事情

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

那么你可以在这样的功能中访问高度：

func keyboardWillShow(notification:NSNotification) {
    let userInfo:NSDictionary = notification.userInfo!
    let keyboardFrame:NSValue = userInfo.valueForKey(UIKeyboardFrameEndUserInfoKey) as! NSValue
    let keyboardRectangle = keyboardFrame.CGRectValue()
    let keyboardHeight = keyboardRectangle.height
}