visionOS 27: UILookToScrollInteraction example

ReaderViewController.swift

import UIKit

// Look to Scroll is a visionOS feature exposed through UIKit.

@available(visionOS 27.0, *)
final class ReaderViewController: UIViewController {

    private let scrollView = UIScrollView()
    private let contentLabel = UILabel()
    private let controlsView = UIVisualEffectView(
        effect: UIBlurEffect(style: .systemMaterial)
    )

    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .systemBackground

        scrollView.translatesAutoresizingMaskIntoConstraints = false
        scrollView.lookToScrollAxes = .vertical
        view.addSubview(scrollView)

        contentLabel.translatesAutoresizingMaskIntoConstraints = false
        contentLabel.numberOfLines = 0
        contentLabel.font = .preferredFont(forTextStyle: .body)
        contentLabel.adjustsFontForContentSizeCategory = true
        contentLabel.text = Array(
            repeating: """
            Look to Scroll is designed for large, meaningful content such as articles, notes, messages, and browsing surfaces. The system can scroll the view when the user looks near its scrolling boundary.

            """,
            count: 18
        ).joined()
        scrollView.addSubview(contentLabel)

        controlsView.translatesAutoresizingMaskIntoConstraints = false
        controlsView.layer.cornerRadius = 18
        controlsView.clipsToBounds = true

        let button = UIButton(
            configuration: .filled(),
            primaryAction: UIAction(
                title: "Bookmark",
                image: UIImage(systemName: "bookmark")
            ) { _ in
                print("Bookmarked")
            }
        )

        button.translatesAutoresizingMaskIntoConstraints = false
        controlsView.contentView.addSubview(button)

        NSLayoutConstraint.activate([
            button.leadingAnchor.constraint(equalTo: controlsView.contentView.leadingAnchor, constant: 12),
            button.trailingAnchor.constraint(equalTo: controlsView.contentView.trailingAnchor, constant: -12),
            button.topAnchor.constraint(equalTo: controlsView.contentView.topAnchor, constant: 12),
            button.bottomAnchor.constraint(equalTo: controlsView.contentView.bottomAnchor, constant: -12)
        ])

        controlsView.addInteraction(
            UILookToScrollInteraction.exclusionRegion()
        )

        view.addSubview(controlsView)

        NSLayoutConstraint.activate([
            scrollView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            scrollView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            scrollView.topAnchor.constraint(equalTo: view.topAnchor),
            scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor),

            contentLabel.leadingAnchor.constraint(equalTo: scrollView.contentLayoutGuide.leadingAnchor, constant: 24),
            contentLabel.trailingAnchor.constraint(equalTo: scrollView.contentLayoutGuide.trailingAnchor, constant: -24),
            contentLabel.topAnchor.constraint(equalTo: scrollView.contentLayoutGuide.topAnchor, constant: 24),
            contentLabel.bottomAnchor.constraint(equalTo: scrollView.contentLayoutGuide.bottomAnchor, constant: -80),
            contentLabel.widthAnchor.constraint(equalTo: scrollView.frameLayoutGuide.widthAnchor, constant: -48),

            controlsView.trailingAnchor.constraint(equalTo: view.safeAreaLayoutGuide.trailingAnchor, constant: -16),
            controlsView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor, constant: -16)
        ])
    }
}