使用自动布局将子视图添加到另一个子视图

Question

我确定我在这里缺少一些愚蠢的东西，但是我有mainView，subviewA和subviewB。我试图将subviewB添加到subviewA并将其锚定在subviewA内，但是它没有锚定（只是保留在左上角。但是，如果我将subviewB添加到mainView然后锚定它，则可以正常工作。

示例（使用我认为是不言自明的自定义锚定功能）：

addSubview(questionContainerView)
questionContainerView.anchor(topAnchor, left: leftAnchor, bottom: centerYAnchor, right: rightAnchor, topConstant: 0, leftConstant: 0, bottomConstant: 0, rightConstant: 0, widthConstant: 0, heightConstant: 0)


// does not work
questionContainerView.addSubview(questionTextLabel)
questionTextLabel.anchor(questionContainerView.topAnchor, left: questionContainerView.leftAnchor, bottom: questionContainerView.bottomAnchor, right: questionContainerView.rightAnchor, topConstant: 25, leftConstant: 10, bottomConstant: 25, rightConstant: 10, widthConstant: 0, heightConstant: 0)

// does work
addSubview(questionTextLabel)
questionTextLabel.anchor(questionContainerView.topAnchor, left: questionContainerView.leftAnchor, bottom: questionContainerView.bottomAnchor, right: questionContainerView.rightAnchor, topConstant: 25, leftConstant: 10, bottomConstant: 25, rightConstant: 10, widthConstant: 0, heightConstant: 0)

Answer 1

您不能将同一视图添加到两个单独的父视图。将其添加到其他视图后，它将从上一个视图中删除。如果要在两个视图上使用标签视图，只需创建它的两个实例。

forEach

Answer 2

我尝试了使用不同背景颜色的相同代码，但发现没有问题，也许是因为背景颜色相同，所以它不可见。

请在下面找到代码

        self.view.addSubview(questionContainerView)
    questionContainerView.anchor(top: self.view.topAnchor, left: self.view.leftAnchor, bottom: self.view.centerYAnchor, right: self.view.rightAnchor, topConstant: 0, leftConstant: 0, bottomConstant: 0, rightConstant: 0, widthConstant: 0, heightConstant: 0)
    questionContainerView.backgroundColor = .blue

    questionContainerView.addSubview(questionTextLabel)
    questionTextLabel.anchor(top: questionContainerView.topAnchor, left: questionContainerView.leftAnchor, bottom: questionContainerView.bottomAnchor, right: questionContainerView.rightAnchor, topConstant: 25, leftConstant: 10, bottomConstant: 25, rightConstant: 10, widthConstant: 0, heightConstant: 0)
    questionTextLabel.backgroundColor = .black