Enhance the accessibility of your reading app

// Link text elements together with navigation APIs

import UIKit

class TravelGuidePageController: UIViewController {

    var paragraphs: [TravelGuideParagraph]

    func configureNavigationElements() {
        for (index, paragraph) in paragraphs.enumerated() {
            if index + 1 < paragraphs.count {
                paragraph.accessibilityNextTextNavigationElement = paragraphs[index + 1]
            }
            if index - 1 >= 0 {
                paragraph.accessibilityPreviousTextNavigationElement = paragraphs[index - 1]
            }
        }
    }
}

// Link text elements together with a linked group

import SwiftUI

struct PageView : View {
    @Namespace private var pageNamespace
    var paragraphs: [String
    var pageNumber: Int

    var body: some View {
        Text(paragraphs[0])
            .textSelection(.enabled)
            .accessibilityLinkedGroup(id: pageNumber, in: pageNamespace)

        Text(paragraphs[1])
            .textSelection(.enabled)
            .accessibilityLinkedGroup(id: pageNumber, in: pageNamespace)
    }
}

// Turn pages automatically after reading

import UIKit

class TravelGuidePageController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        self.lastParagraphView.accessibilityTraits.insert(.causesPageTurn)
    }

    override func accessibilityScroll(_ direction: UIAccessibilityScrollDirection) -> Bool {
        moveToPage(direction)
        var scrollString = "Page \(currentPage) of \(pages.count)"
        UIAccessibility.post(notification: .pageScrolled, argument: scrollString)
        return true
    }
}

// Add actions to the editor rotor

import UIKit

class TravelGuideParagraph: UITextView {

    override var accessibilityCustomActions: [UIAccessibilityCustomAction]? {
        get {
            let saveAction = UIAccessibilityCustomAction(name: "Save Recommendation") { _ in
                self.saveRecommendation()
            }
            saveAction.category = UIAccessibilityCustomAction.editCategory
            return (super.accessibilityCustomActions ?? []) + [saveAction]
        }
        set { }
    }

    private func saveRecommendation() -> Bool {
        ...
        return true
    }
}

// Adopt UITextInput

import UIKit

class ScannedPage: UIView, UITextInput {

    override init(frame: CGRect) {
        super.init(frame: frame)
        let interaction = UITextInteraction(for: .nonEditable)
        interaction.textInput = self
        addInteraction(interaction)
    }
   
    func selectionRects(for range: UITextRange) -> [UITextSelectionRect] {
        var rects: [UITextSelectionRect] = []

        let startLine = lineIndex(for: range.start)
        let endLine = lineIndex(for: range.end)

        for line in startLine...endLine {
            let rect = selectionRectFromImage(for: range, in: line)
            rects.append(rect)
        }

        return rects
    }
  
    func text(in range: UITextRange) -> String? {
        let nsRange = nsRange(from: range)
        guard let range = Range(nsRange, in: scannedText) else {
            return nil
        }
        return String(scannedText[range])
    }

    var tokenizer: any UITextInputTokenizer { CustomHandwritingTokenizer(textInput: self) }

    weak var inputDelegate: UITextInputDelegate?
  
      var selectedTextRange: UITextRange? {
        // Update visuals when assistive technologies change selection
        willSet { inputDelegate?.selectionWillChange(self) }
        didSet { inputDelegate?.selectionDidChange(self) }
    }
  
}