Example: UIStackView in UIScrollView

1-uistackview-in-uiscrollview.playground.swift

import UIKit
import PlaygroundSupport

let scrollView = UIScrollView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
scrollView.backgroundColor = .red

let stackView = UIStackView(frame: CGRect(x: 0, y: 0, width: 1000, height: 100))
stackView.backgroundColor = .gray
stackView.axis = .horizontal
stackView.spacing = 10
stackView.distribution = .fillEqually
scrollView.addSubview(stackView)

stackView.topAnchor.constraint(equalTo: scrollView.topAnchor, constant: 0).isActive = true
stackView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor, constant: 0).isActive = true
stackView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor, constant: 0).isActive = true
stackView.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor, constant: 0).isActive = true

let whiteRectView = { () -> UIView in 
    let view = UIView()
    view.backgroundColor = .white
    return view
}
(0..<10).forEach { _ in stackView.addArrangedSubview(whiteRectView()) }

PlaygroundPage.current.liveView = scrollView

2-demo.md