如何以编程方式设置内容拥抱和压缩

Question

当我隐藏其中一个视图时，我想给隐藏秀设置动画。因此我使用了具有优先权的内容来对其进行动画处理，但是失败了，它在视图之间存在间隙。在这里，我向您展示ui和我的代码

这是上图中的3个uiview代码

    scrollView.addSubview(chooseScheduleDropDown)
        chooseScheduleDropDown.translatesAutoresizingMaskIntoConstraints = false
        chooseScheduleDropDown.setContentCompressionResistancePriority(.required, for: .vertical)
        NSLayoutConstraint.activate([
            chooseScheduleDropDown.centerXAnchor.constraint(equalTo: scrollView.centerXAnchor),
            chooseScheduleDropDown.topAnchor.constraint(equalTo: scrollView.topAnchor),
            chooseScheduleDropDown.widthAnchor.constraint(equalToConstant: 285),
            chooseScheduleDropDown.heightAnchor.constraint(equalToConstant: 60)
        ])

        scrollView.addSubview(entryView)
        entryView.isHidden = true
        entryView.setContentHuggingPriority(.defaultLow, for: .vertical)
        entryView.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            entryView.centerXAnchor.constraint(equalTo: scrollView.centerXAnchor),
            entryView.topAnchor.constraint(equalTo: chooseScheduleDropDown.bottomAnchor, constant: topPadding),
            entryView.widthAnchor.constraint(equalToConstant: 285),
            entryView.heightAnchor.constraint(equalToConstant: 60)
        ])

        scrollView.addSubview(chooseDateView)
        chooseDateView.setContentHuggingPriority(.defaultLow, for: .vertical)
        chooseDateView.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            chooseDateView.centerXAnchor.constraint(equalTo: scrollView.centerXAnchor),
            chooseDateView.topAnchor.constraint(equalTo: entryView.bottomAnchor, constant: topPadding),
            chooseDateView.widthAnchor.constraint(equalToConstant: 285),
            chooseDateView.heightAnchor.constraint(equalToConstant: 60)
        ])

Answer 1

执行

var hCon:NSLayoutConstraint! 
hCon = entryView.heightAnchor.constraint(equalToConstant: 60) 
hCon.isActive = true