Customize the Annotations List in Swift for iOS

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//
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//  Copyright © 2021-2025 PSPDFKit GmbH. All rights reserved.
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//
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//  The Nutrient sample applications are licensed with a modified BSD license.
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//  Please see License for details. This notice may not be removed from this file.
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//
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import PSPDFKit
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import PSPDFKitUI
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class AnnotationListExample: Example {
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    override init() {
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        super.init()
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        title = "Customizing the Annotation List"
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        contentDescription = "Customize the annotation cell in AnnotationTableViewController."
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        category = .viewCustomization
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        priority = 70
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    }
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    override func invoke(with delegate: ExampleRunnerDelegate) -> UIViewController? {
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        let guide = AssetLoader.document(for: .welcome)
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        let controller = PDFViewController(document: guide) { builder in
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            builder.overrideClass(AnnotationCell.self, with: CustomAnnotationCell.self)
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            builder.overrideClass(AnnotationTableViewController.self, with: AnnotationListController.self)
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        }
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        controller.documentInfoCoordinator.availableControllerOptions = [.annotations]
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        // Simulate tapping on the outline button.
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        DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(1)) {
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            controller.documentInfoCoordinator.present(
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                to: controller,
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                options: nil,
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                sender: controller.outlineButtonItem,
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                animated: true,
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                completion: nil
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            )
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        }
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        return controller
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    }
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}
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private class CustomAnnotationCell: AnnotationCell {
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    var isShared: Bool {
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        didSet {
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            sharingStateLabel.text = isShared ? "Shared" : "Not Shared"
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            // Ensure the size and placement are up to date
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            sharingStateLabel.sizeToFit()
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            setNeedsLayout()
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        }
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    }
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    // Note: This isn’t the greatest UI. A smaller sharing indicator would be nicer.
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    private var sharingStateLabel: UILabel
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    override init(style: UITableViewCell.CellStyle, reuseIdentifier: String?) {
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        isShared = false
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        sharingStateLabel = UILabel()
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        sharingStateLabel.textColor = .psc_secondaryLabel
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        super.init(style: style, reuseIdentifier: reuseIdentifier)
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        accessoryView = sharingStateLabel
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    }
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    required init?(coder: NSCoder) {
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        fatalError("init(coder:) has not been implemented and isn’t needed")
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    }
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}
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private class AnnotationListController: AnnotationTableViewController {
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    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
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        let anyCell = super.tableView(tableView, cellForRowAt: indexPath)
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        guard let cell = anyCell as? CustomAnnotationCell else {
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            return anyCell
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        }
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        // Our superclass sets the annotation on the cell, so we know we may force unwrap.
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        let annotation = cell.annotation!
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        cell.isShared = sharedState(for: annotation)
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        return cell
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    }
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    private var sharedStateByAnnotationID: [String: Bool] = [:]
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    private func sharedState(for annotation: Annotation) -> Bool {
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        sharedStateByAnnotationID[annotation.id] ?? false
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    }
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    private func toggleSharedState(for annotation: Annotation) -> Bool {
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        let desiredState = !sharedState(for: annotation)
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        sharedStateByAnnotationID[annotation.id] = desiredState
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        return desiredState
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    }
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    override func tableView(_ tableView: UITableView, trailingSwipeActionsConfigurationForRowAt indexPath: IndexPath) -> UISwipeActionsConfiguration? {
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        guard let cell = tableView.cellForRow(at: indexPath) as? CustomAnnotationCell else {
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            return super.tableView(tableView, trailingSwipeActionsConfigurationForRowAt: indexPath)
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        }
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        let action = UIContextualAction(
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            style: .normal,
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            title: cell.isShared ? "Unshare" : "Share"
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        ) { [weak cell, weak self] _, _, completion in
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            guard let cell, let self else {
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                return completion(false)
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            }
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            cell.isShared = self.sharedState(for: cell.annotation!)
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            completion(true)
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        }
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        return UISwipeActionsConfiguration(actions: [action])
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    }
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}