ios - 在 iOS 9 上更改隐藏属性时，UIStackView 不会设置动画

Question

我正在使用 Stack View 创建一种表 UI，我在 StackView 中有 6 个 View ，0、2、4 是可见的，1、3、5 是隐藏的。当点击其中一个可见 View 时，我希望“打开”隐藏的 View 之一。

我的这段代码在 iOS 10 上运行良好，但出于某种原因我无法理解它在 iOS 9 上运行不佳。

请注意，如果我加载所有打开的 View ，关闭动画将起作用，但在将隐藏属性设置为 false 时它不会打开。

这是我的代码-

编辑 经过一些调试后，view height constraint 并没有从隐藏中恢复，它的 frame 仍然高度为 0。

 import UIKit

class DeckView: UIView {

}

class ViewController: UIViewController {

var scrollView: UIScrollView!
var stackView: UIStackView!

override func viewDidLoad() {
    super.viewDidLoad()

    scrollView = UIScrollView()
    scrollView.translatesAutoresizingMaskIntoConstraints = false
    view.addSubview(scrollView)

    view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[scrollView]|", options: .alignAllCenterX, metrics: nil, views: ["scrollView": scrollView]))
    view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[scrollView]|", options: .alignAllCenterX, metrics: nil, views: ["scrollView": scrollView]))


    stackView = UIStackView()
    stackView.translatesAutoresizingMaskIntoConstraints = false
    stackView.spacing = 0
    stackView.alignment = .center
    stackView.distribution = .fillProportionally
    stackView.axis = .vertical
    scrollView.addSubview(stackView)

    scrollView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[stackView]|", options: NSLayoutFormatOptions.alignAllCenterX, metrics: nil, views: ["stackView": stackView]))
    scrollView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[stackView]|", options: NSLayoutFormatOptions.alignAllCenterX, metrics: nil, views: ["stackView": stackView]))


    for i in 0 ..< 8 {
        let view  = DeckView()
        view.tag = i
        view.translatesAutoresizingMaskIntoConstraints = false
        view.widthAnchor.constraint(equalToConstant: UIScreen.main.bounds.width).isActive = true
        view.isUserInteractionEnabled = true

        if i%2 == 0 {
            view.backgroundColor   = UIColor.magenta
            let constriant = view.heightAnchor.constraint(equalToConstant:160)
            constriant.priority = 999
            view.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(self.openDeck(_:))))
            view.addConstraint(constriant)

        } else {
            view.backgroundColor   = UIColor.red
            let constriant = view.heightAnchor.constraint(equalToConstant:160)
            constriant.priority = 999
            view.addConstraint(constriant)
            view.isHidden = false
        }

        stackView.addArrangedSubview(view)
    }
}

func openDeck(_ sender:UIGestureRecognizer) {
    if let view = sender.view as? DeckView,
    let childView = stackView.viewWithTag(view.tag + 1) {
            UIView.animate(withDuration: 0.4, animations: {
                childView.isHidden = !childView.isHidden
            })
    }
}
}

Answer 1

1. 保持 View 的高度优先级低于 1000(为 999)。
2. 如果它已经隐藏，则不要设置setHidden:true(这是 UIStackView 的错误)