UIStackView隐藏视图动画

在iOS 11中，a中隐藏动画的行为UIStackView已更改，但是我无法在任何地方找到该文档。

iOS 10

iOS 11

两者中的代码是这样的：

UIView.animate(withDuration: DiscoverHeaderView.animationDuration,
                       delay: 0.0,
                       usingSpringWithDamping: 0.9,
                       initialSpringVelocity: 1,
                       options: [],
                       animations: {
                            clear.isHidden = hideClear
                            useMyLocation.isHidden = hideLocation
                        },
                       completion: nil)

如何在iOS 11上还原以前的行为？

只是有同样的问题。该修复程序将添加stackView.layoutIfNeeded()到动画块中。stackView您要隐藏的物品的容器在哪里？

UIView.animate(withDuration: DiscoverHeaderView.animationDuration,
                   delay: 0.0,
                   usingSpringWithDamping: 0.9,
                   initialSpringVelocity: 1,
                   options: [],
                   animations: {
                        clear.isHidden = hideClear
                        useMyLocation.isHidden = hideLocation
                        stackView.layoutIfNeeded()
                    },
                   completion: nil)

不确定为什么这会突然成为iOS 11中的问题，但公平地说，这一直是推荐的方法。

Swift 4扩展程序：

// MARK: - Show hide animations in StackViews

extension UIView {

func hideAnimated(in stackView: UIStackView) {
    if !self.isHidden {
        UIView.animate(
            withDuration: 0.35,
            delay: 0,
            usingSpringWithDamping: 0.9,
            initialSpringVelocity: 1,
            options: [],
            animations: {
                self.isHidden = true
                stackView.layoutIfNeeded()
            },
            completion: nil
        )
    }
}

func showAnimated(in stackView: UIStackView) {
    if self.isHidden {
        UIView.animate(
            withDuration: 0.35,
            delay: 0,
            usingSpringWithDamping: 0.9,
            initialSpringVelocity: 1,
            options: [],
            animations: {
                self.isHidden = false
                stackView.layoutIfNeeded()
            },
            completion: nil
        )
    }
}
}

可接受答案的注释中已经提到了它，但这是我的问题，这里没有任何答案，因此：

确保永远不要isHidden = true在已经隐藏的视图上进行设置。这会弄乱堆栈视图。

我想分享这一功能，该功能非常适合在中隐藏和显示许多视图UIStackView，因为在我之前使用的所有代码中，由于需要从某些图层中移除removeAnimation，所以无法正常工作：

extension UIStackView {
    public func make(viewsHidden: [UIView], viewsVisible: [UIView], animated: Bool) {
        let viewsHidden = viewsHidden.filter({ $0.superview === self })
        let viewsVisible = viewsVisible.filter({ $0.superview === self })

        let blockToSetVisibility: ([UIView], _ hidden: Bool) -> Void = { views, hidden in
            views.forEach({ $0.isHidden = hidden })
        }

        // need for smooth animation
        let blockToSetAlphaForSubviewsOf: ([UIView], _ alpha: CGFloat) -> Void = { views, alpha in
            views.forEach({ view in
                view.subviews.forEach({ $0.alpha = alpha })
            })
        }

        if !animated {
            blockToSetVisibility(viewsHidden, true)
            blockToSetVisibility(viewsVisible, false)
            blockToSetAlphaForSubviewsOf(viewsHidden, 1)
            blockToSetAlphaForSubviewsOf(viewsVisible, 1)
        } else {
            // update hidden values of all views
            // without that animation doesn't go
            let allViews = viewsHidden + viewsVisible
            self.layer.removeAllAnimations()
            allViews.forEach { view in
                let oldHiddenValue = view.isHidden
                view.layer.removeAllAnimations()
                view.layer.isHidden = oldHiddenValue
            }

            UIView.animate(withDuration: 0.3,
                           delay: 0.0,
                           usingSpringWithDamping: 0.9,
                           initialSpringVelocity: 1,
                           options: [],
                           animations: {

                            blockToSetAlphaForSubviewsOf(viewsVisible, 1)
                            blockToSetAlphaForSubviewsOf(viewsHidden, 0)

                            blockToSetVisibility(viewsHidden, true)
                            blockToSetVisibility(viewsVisible, false)
                            self.layoutIfNeeded()
            },
                           completion: nil)
        }
    }
}

扩展以隐藏/显示单个元素

它不是100％相关的，但是，如果您正在寻找一种简洁的方法来隐藏单个UIView元素（在堆栈视图或其他任何位置），则可以使用我做的这个简单扩展：

extension UIView {
    func isHiddenAnimated(value: Bool, duration: Double = 0.2) {
        UIView.animate(withDuration: duration) { [weak self] in self?.isHidden = value }
    }
}

我用它方便地用单行代码在堆栈视图中隐藏/显示带有动画的元素。例：

validatableButton.isHiddenAnimated(value: false)

希望这可以节省别人几个小时的挫败感。

动画隐藏和同时显示多个UIStackView子视图是一团糟。

在某些情况下，动画块中的.isHidden更改会正确显示，直到下一个动画，然后才会忽略.isHidden。我为此找到的唯一可靠的技巧是在动画块的完成部分重复.isHidden指令。

    let time = 0.3

    UIView.animate(withDuration: time, animations: {

        //shows
        self.googleSignInView.isHidden = false
        self.googleSignInView.alpha = 1
        self.registerView.isHidden = false
        self.registerView.alpha = 1

        //hides
        self.usernameView.isHidden = true
        self.usernameView.alpha = 0
        self.passwordView.isHidden = true
        self.passwordView.alpha = 0

        self.stackView.layoutIfNeeded()

    }) { (finished) in

        self.googleSignInView.isHidden = false
        self.registerView.isHidden = false
        self.usernameView.isHidden = true
        self.passwordView.isHidden = true
    }