Ios UIKeyboardWillHideNotification动画中的延迟

我已经注册了两个UIKeyboardNotification（keyboardWillShow和keyboardWillHide），两个都被触发。当textfield移回原始位置的动画仅在键盘消失后触发时，问题就出现了。是否有任何方法可以减少收到通知和设置文本字段动画之间的延迟

func keyboardWillShow(notification: NSNotification) {
    let info = notification.userInfo!
    let keyboardFrame : CGRect = (info[UIKeyboardFrameEndUserInfoKey] as! NSValue).CGRectValue()
    duration = (info[UIKeyboardAnimationDurationUserInfoKey]?.doubleValue)
    let rawAnimationCurve = (notification.userInfo![UIKeyboardAnimationCurveUserInfoKey] as! NSNumber).unsignedIntValue << 16
    animationCurve = UIViewAnimationOptions(rawValue: UInt(rawAnimationCurve))
    let moveAmount = keyboardFrame.height
    UIView.animateWithDuration(duration!, delay:0, options: animationCurve, animations: {
        self.txtfield.transform = CGAffineTransformMakeTranslation(0.0, -self.moveAmount)
        }, completion:nil)
}

func keyboardWillHide(notification: NSNotification) {
        UIView.animateWithDuration(duration, delay:0, options:animationCurve, animations: {
            self. txtfield.transform = CGAffineTransformMakeTranslation(0.0, 0.0)
            }, completion:nil)
}

func键盘将显示（通知：NSNotification）{
让info=notification.userInfo！
让keyboardFrame:CGRect=（info[UIKeyboardFrameEndUserInfoKey]为！NSValue）.CGRectValue（）
持续时间=（信息[UIKeyboardAnimationDurationUserInfoKey]？.doubleValue）
让rawAnimationCurve=（notification.userInfo！[UIKeyboardAnimationCurveUserInfo]作为！NSNumber）。unsignedIntValue意识到一个问题，这是我的一个粗心错误

增加：

NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(viewController.keyboardDidHide), name: UIKeyboardWillHideNotification, object: nil)

而不是：

NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(viewController.keyboardWillHide), name: UIKeyboardWillHideNotification, object: nil)