在iOS设备中出现键盘时滑动UIView

Question

我知道关于键盘出现在iOS上时滑动UIView的问题也很多。 但是，我的实现似乎有一个我未曾提及的问题。 发生幻灯片动画时，它不是从屏幕顶部开始，而是我从较低的原点开始，然后又向上移动到屏幕顶部。

这是我为实现此上滑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)
    }
}

我不确定我缺少什么。 看我的view.frame值，我有一个负的origin.y，正如我期望的那样。 有人看到我想念的东西吗？

编辑 ：aimak用户提出了一个非常明智的建议，即我将动画更改为（不推荐使用）块调用版本。 有趣的是，动画仍然被破坏，但是方式不同。 这是经过修改的代码，以及有关最新动画调用发生的情况的屏幕截图。

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

这可能无法完全帮助您，但是自iOS 4+起不鼓励使用这些动画方法：

不鼓励在iOS 4.0及更高版本中使用此方法。 您应该改用基于块的动画方法来指定动画。

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

您是否尝试过基于块的API？

编辑：这是自动布局的问题！

好的，我想我知道了：您是否使用自动版式？ 如果是这样，则UIViewController.view的子视图可能具有view.top = 0的约束，并且该约束永远不会被破坏。 如果要获得所需的动画，请考虑：1.将每个子视图嵌入scrollView中（然后为contentOffet.y动画），或2.删除/编辑view.top约束。

Answer 2

正如aimak所指出的那样，问题在于我使用的是AutoLayout，并且约束覆盖了我对框架所做的修改。 为了解决这个问题，我将所有内容移到了滚动视图中。 现在，我利用滚动scrollview来在键盘显示时偏移。

这是我必须提供滚动行为的帮助器类。 请注意，我现在通过了滚动视图。

public class KeyboardScrollViewHelper {

    private var scrollView: UIScrollView?
    private var isScrolled = false

    private dynamic func keyboardWillShow(sender: NSNotification) {
        guard !isScrolled else {
            return
        }

        slideViewVerticallyForKeyboardHeight(sender, directionUp: true)
    }

    private dynamic func keyboardWillHide(sender: NSNotification) {
        guard isScrolled else {
            return
        }

        slideViewVerticallyForKeyboardHeight(sender, directionUp: false)
    }

    private func slideViewVerticallyForKeyboardHeight(notification: NSNotification, directionUp: Bool) {

        guard let scrollView = self.scrollView else {
            return
        }

        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 scrollViewOffset: CGFloat = 0
        if directionUp {
            scrollViewOffset = scrollView.contentOffset.y + keyboardHeight
            isScrolled = true
        } else {
            scrollViewOffset =  scrollView.contentOffset.y - keyboardHeight
            isScrolled = false
        }

        scrollViewOffset = max(0, scrollViewOffset)

        UIView.animateWithDuration(animationDuration, delay: 0, options: animationCurve.toOptions(), animations: {
            scrollView.contentOffset.y = scrollViewOffset
            }, completion: nil)
    }

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

    public func unregisterViewSlideOnKeyboard() {
        scrollView?.contentOffset = CGPointZero

        scrollView = nil
        NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillShowNotification, object: nil)
        NSNotificationCenter.defaultCenter().removeObserver(self, name: UIKeyboardWillHideNotification, object: nil)
    }
}