如何以编程方式在水平线性布局中均匀分布子视图？

import UIKit

// 创建父视图
let containerView = UIView()
containerView.translatesAutoresizingMaskIntoConstraints = false

// 创建子视图
let view1 = UIView()
view1.translatesAutoresizingMaskIntoConstraints = false
let view2 = UIView()
view2.translatesAutoresizingMaskIntoConstraints = false
let view3 = UIView()
view3.translatesAutoresizingMaskIntoConstraints = false

// 将子视图添加到父视图
containerView.addSubview(view1)
containerView.addSubview(view2)
containerView.addSubview(view3)

// 设置子视图的约束
NSLayoutConstraint.activate([
    // 子视图1的宽度和位置
    view1.widthAnchor.constraint(equalTo: containerView.widthAnchor, multiplier: 1/3),
    view1.leadingAnchor.constraint(equalTo: containerView.leadingAnchor),
    view1.topAnchor.constraint(equalTo: containerView.topAnchor),
    view1.bottomAnchor.constraint(equalTo: containerView.bottomAnchor),
    
    // 子视图2的宽度和位置
    view2.widthAnchor.constraint(equalTo: containerView.widthAnchor, multiplier: 1/3),
    view2.leadingAnchor.constraint(equalTo: view1.trailingAnchor),
    view2.topAnchor.constraint(equalTo: containerView.topAnchor),
    view2.bottomAnchor.constraint(equalTo: containerView.bottomAnchor),
    
    // 子视图3的宽度和位置
    view3.widthAnchor.constraint(equalTo: containerView.widthAnchor, multiplier: 1/3),
    view3.leadingAnchor.constraint(equalTo: view2.trailingAnchor),
    view3.topAnchor.constraint(equalTo: containerView.topAnchor),
    view3.bottomAnchor.constraint(equalTo: containerView.bottomAnchor)
])

// 添加父视图到主视图
let mainView = UIView()
mainView.addSubview(containerView)

// 设置父视图的约束
NSLayoutConstraint.activate([
    containerView.leadingAnchor.constraint(equalTo: mainView.leadingAnchor),
    containerView.trailingAnchor.constraint(equalTo: mainView.trailingAnchor),
    containerView.topAnchor.constraint(equalTo: mainView.topAnchor),
    containerView.bottomAnchor.constraint(equalTo: mainView.bottomAnchor)
])