ios - 在 iOS 中出现键盘时滑动 UIView

Question

我知道这里有很多关于当键盘出现在 iOS 上时滑动 UIView 的类似问题。但是，我的实现似乎存在一个我没有看到提到的问题。当我的幻灯片动画出现时，它并没有像我期望的那样从屏幕顶部开始，而是从较低的原点开始并向上移动回到屏幕顶部。

这是我为实现这种向上滑动行为而创建的类扩展。

public extension UIViewController {

    private dynamic func keyboardWillShow(sender: NSNotification) {
        if view.frame.origin.y == 0 {
            slideViewVerticallyForKeyboardHeight(sender, directionUp: true)
        }
    }

    private dynamic func keyboardWillHide(sender: NSNotification) {
        if view.frame.origin.y < 0 {
            slideViewVerticallyForKeyboardHeight(sender, directionUp: false)
        }
    }

    private func slideViewVerticallyForKeyboardHeight(notification: NSNotification, directionUp: Bool) {
        UIView.beginAnimations(nil, context: nil)
        let keyboardHeight: CGFloat = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue().height ?? 0.0
        let animationDuration = notification.userInfo?[UIKeyboardAnimationDurationUserInfoKey]?.doubleValue ?? 0.0
        let animationCurve: Int = notification.userInfo?[UIKeyboardAnimationCurveUserInfoKey]?.integerValue ?? 0
        UIView.setAnimationDuration(animationDuration)
        UIView.setAnimationCurve(UIViewAnimationCurve(rawValue: animationCurve)!)
        UIView.setAnimationBeginsFromCurrentState(true)

        var newFrameRect = view.frame
        if directionUp {
            newFrameRect.origin.y -= keyboardHeight
            newFrameRect.size.height += keyboardHeight
        } else {
            newFrameRect.origin.y += keyboardHeight
            newFrameRect.size.height -= keyboardHeight
        }
        view.frame = newFrameRect
        UIView.commitAnimations()
    }

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

    public func unregisterViewSlideOnKeyboard() {
        NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillShowNotification, object: nil)
        NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillHideNotification, object: nil)
    }
}

我不确定我错过了什么。看看我的 view.frame 值，正如我所期望的，我的 origin.y 为负值。有人看到我错过了什么吗？

编辑:用户aiak提出了非常明智的建议，即我更改为(未弃用的)动画 block 调用版本。有趣的是，动画仍然被破坏，但以不同的方式。以下是修改后的代码以及更新的动画调用所发生情况的屏幕截图。

private func slideViewVerticallyForKeyboardHeight(notification: NSNotification, directionUp: Bool) {
    UIView.beginAnimations(nil, context: nil)
    let keyboardHeight: CGFloat = (notification.userInfo?[UIKeyboardFrameBeginUserInfoKey] as? NSValue)?.CGRectValue().height ?? 0.0
    let animationDuration = notification.userInfo?[UIKeyboardAnimationDurationUserInfoKey]?.doubleValue ?? 0.0
    let animationCurve: UIViewAnimationCurve = UIViewAnimationCurve(rawValue: notification.userInfo?[UIKeyboardAnimationCurveUserInfoKey]?.integerValue ?? 0)!
    var newFrameRect = view.frame
    if directionUp {
        newFrameRect.origin.y -= keyboardHeight
        newFrameRect.size.height += keyboardHeight
    } else {
        newFrameRect.origin.y += keyboardHeight
        newFrameRect.size.height -= keyboardHeight
    }

    UIView.animateWithDuration(animationDuration, delay: 0, options: animationCurve.toOptions(), animations: {
            self.view.frame = newFrameRect
        }, completion: nil)
}

Answer 1

这可能没有完全帮助，但自 iOS 4+ 以来不鼓励使用这些动画方法:

Use of this method is discouraged in iOS 4.0 and later. You should use the block-based animation methods to specify your animations instead.

引用:https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIView_Class/#//apple_ref/occ/clm/UIView/commitAnimations

您尝试过基于 block 的 API 吗？

编辑:这是自动布局问题!

好的，我想我知道了:你们使用自动布局吗？如果是这样，UIViewController.view 的 subview 可能对 view.top = 0 有约束，并且该约束永远不会被打破。如果您想实现您想要的动画，请考虑:1. 将每个 subview 嵌入 scrollView 中(然后为 contentOffet.y 更改设置动画)或 2. 删除/编辑您的 view.top 约束