ios - iOS8出现键盘的动画速度是多少？

Question

以下是当键盘出现时向上移动的 textField 和 toolBar 的动画。

    baseConstraint.constant = 211
    self.view.setNeedsUpdateConstraints()

    UIView.animateWithDuration(0.30, animations: {
        self.view.layoutIfNeeded()
        })

它很接近但不完全相同。你会如何修改上面的动画？

编辑:

这是使用下面答案的最终代码!

   func keyboardWillShow(aNotification: NSNotification)    {

        let duration = aNotification.userInfo.objectForKey(UIKeyboardAnimationDurationUserInfoKey) as Double
        let curve = aNotification.userInfo.objectForKey(UIKeyboardAnimationCurveUserInfoKey) as UInt

        self.view.setNeedsLayout()
        baseConstraint.constant = 211
        self.view.setNeedsUpdateConstraints()

        UIView.animateWithDuration(duration, delay: 0, options: UIViewAnimationOptions.fromMask(curve), animations: {
        self.view.layoutIfNeeded()
        }, completion: {
        (value: Bool) in println()
        })
}

Answer 1

可以从keyboardWillShow: notifications上的userInfo字典中获取动画时长和动画曲线。

先注册通知

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardWillShowNotification object:nil];

然后从通知 userInfo 键中获取值。

- (void)keyboardWillShow:(NSNotification*)notification {
    NSNumber *duration = [notification.userInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey];
    NSNumber *curve = [notification.userInfo objectForKey: UIKeyboardAnimationCurveUserInfoKey];

   // Do stuff with these values.
}

这些键还有很多，您也可以从 UIKeyboardWillDismiss 通知中获取它们。

此功能一直可用到 iOS 3.0 :D

这是文档:

https://developer.apple.com/library/ios/documentation/uikit/reference/UIWindow_Class/UIWindowClassReference/UIWindowClassReference.html#//apple_ref/doc/constant_group/Keyboard_Notification_User_Info_Keys

快速版本

NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(_:)), name: UIResponder.keyboardWillShowNotification, object: nil)

@objc func keyboardWillShow(_ notification: Notification) {
    let duration = notification.userInfo?[UIResponder.keyboardAnimationDurationUserInfoKey]
    let curve = notification.userInfo?[UIResponder.keyboardAnimationCurveUserInfoKey]
}