在stackView中以编程方式布局子视图

// 创建一个垂直方向的stackView
let stackView = UIStackView()
stackView.axis = .vertical
stackView.alignment = .fill
stackView.distribution = .fill
stackView.spacing = 10

// 创建子视图
let label1 = UILabel()
label1.text = "Label 1"

let label2 = UILabel()
label2.text = "Label 2"

let label3 = UILabel()
label3.text = "Label 3"

// 将子视图添加到stackView中
stackView.addArrangedSubview(label1)
stackView.addArrangedSubview(label2)
stackView.addArrangedSubview(label3)

// 设置子视图的布局约束
label1.heightAnchor.constraint(equalToConstant: 30).isActive = true
label2.heightAnchor.constraint(equalToConstant: 40).isActive = true
label3.heightAnchor.constraint(equalToConstant: 50).isActive = true

// 将stackView添加到父视图中
view.addSubview(stackView)

// 设置stackView的布局约束
stackView.translatesAutoresizingMaskIntoConstraints = false
stackView.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: 20).isActive = true
stackView.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -20).isActive = true
stackView.topAnchor.constraint(equalTo: view.topAnchor, constant: 20).isActive = true
stackView.bottomAnchor.constraint(equalTo: view.bottomAnchor, constant: -20).isActive = true