UIStackView-为什么堆栈位于另一个堆栈之上？

Question

我试图将一组按钮排列在堆栈视图中。但是，当我使用for-each循环执行此操作时，这些按钮最终会被一个定位在另一个之上吗？

 var stackView: UIStackView = {
    let sView = UIStackView()
    sView.axis = .vertical
    sView.distribution = .fill
    sView.alignment = .center
    return sView
}()

var optionTitles = ["Sign in", "sign out"]

for title in optionTitles{
        let btn = UIButton()
        btn.setTitle(title, for: .normal)
        btn.backgroundColor = optionColour.withAlphaComponent(0.6)
        allButtons.append(btn)
        stackView.addSubview(btn)
    }

    // Auto layout constraints
    for button in allButtons{
        button.translatesAutoresizingMaskIntoConstraints = false
        button.heightAnchor.constraint(equalToConstant: optionHeight).isActive = true
        button.widthAnchor.constraint(equalTo: stackView.widthAnchor).isActive = true
    }

    view.addSubview(stackView)
    stackTopConstraint = stackView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor)
    stackBottomConstraint = stackView.bottomAnchor.constraint(equalTo: view.topAnchor)

    stackView.translatesAutoresizingMaskIntoConstraints = false
    stackView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
    stackTopConstraint!.isActive = true
    stackView.widthAnchor.constraint(equalTo: view.widthAnchor).isActive = true

Answer 1

两件事

1-您需要删除此

button.widthAnchor.constraint(equalTo: stackView.widthAnchor).isActive = true

2-替换

stackView.addSubview(btn) 

使用

stackView.addArrangedSubview(btn) 

Answer 2

您有：

stackTopConstraint = stackView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor)
stackBottomConstraint = stackView.bottomAnchor.constraint(equalTo: view.topAnchor)

您可能在第二行中表示view.bottomAnchor。当然，您不想将堆栈视图的底部限制为视图的 top 。