以编程方式显示和隐藏容器 UIView 及其子视图

Question

我有一个标签和一个并排的按钮，如下所示：

这是通过以下代码创建的：

private func addViewBack() {
    myLabel.translatesAutoresizingMaskIntoConstraints = false
    myLabel.text = "Show my label"

    myButton.addTarget(self, action: #selector(pressed), for: .touchUpInside)
    myButton.setTitleColor(UIColor.lightGray, for: UIControl.State.normal)
    myButton.translatesAutoresizingMaskIntoConstraints = false
    myButton.setTitle("Button", for: .normal)
    myButton.clipsToBounds = true

    containerView.backgroundColor = .red
    containerView.addSubview(myLabel)
    containerView.translatesAutoresizingMaskIntoConstraints = false
    containerView.addSubview(myButton)

    containerView.addConstraint(NSLayoutConstraint(item: myButton, attribute: .centerY, relatedBy: .equal, toItem: myLabel, attribute: .centerY, multiplier: 1, constant: 0))
    containerView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|-8-[myLabel]-8-|", options: [], metrics: nil, views: ["myLabel":myLabel]))
    containerView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-8-[myLabel]", options: [], metrics: nil, views: ["myLabel":myLabel]))
    containerView.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:[myButton]-8-|", options: [], metrics: nil, views: ["myButton":myButton]))
    containerView.layoutIfNeeded()

    self.view.addSubview(containerView)

    self.view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:[topView]-100-[containerView]", options: [], metrics: nil, views: ["containerView":containerView,"topView":viewTop]))
    self.view.addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|-8-[containerView]-8-|", options: [], metrics: nil, views: ["containerView":containerView]))
    self.view.layoutIfNeeded()
}

我有显示和隐藏按钮，按下它们时应该显示和隐藏容器视图，如下所示：

@IBAction func show(_ sender: Any) {

    if let constraint = (containerView.constraints.filter{[=11=].firstAttribute == .height}.first) {
        constraint.isActive = false
    }

    containerView.layoutIfNeeded()
}

@IBAction func hide(_ sender: Any) {
    containerView.heightAnchor.constraint(equalToConstant: 0).isActive = true
    containerView.layoutIfNeeded()

}

使用隐藏操作时，按钮永远不会隐藏，我最终得到这样的结果：

当我添加以下内容时它起作用了：

@IBAction func hide(_ sender: Any) {
    containerView.heightAnchor.constraint(equalToConstant: 0).isActive = true
    myButton.heightAnchor.constraint(equalToConstant: 0).isActive = true
    containerView.layoutIfNeeded()

}

当我按下显示动作时，按钮再也不会像这样再次出现：

如何以编程方式使用自动布局非常简单地显示和隐藏容器视图中的元素？

Answer 1

不要对容器视图进行高度限制 active/inactive，而是将其常量更改为零以隐藏容器视图。如果它的 clipsToBounds 为真，那也将隐藏内容。

以编程方式显示和隐藏容器 UIView 及其子视图

Showing and Hiding a container UIView with its subviews programmatically

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autolayout

swift