Add Text Annotation to PDF in Swift for iOS

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//
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//  Copyright © 2017-2025 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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private protocol InsertTextViewControllerDelegate: NSObjectProtocol {
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    func insertTextViewController(_ controller: InsertTextViewController, didSelectRowAt index: Int)
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}
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private class InsertTextViewController: BaseTableViewController {
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    weak var delegate: InsertTextViewControllerDelegate?
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    let cellReuseIdentifier = "InsertTextViewControllerCell"
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    override func viewDidLoad() {
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        super.viewDidLoad()
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        tableView.register(UITableViewCell.self, forCellReuseIdentifier: cellReuseIdentifier)
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    }
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    // MARK: - UITableViewDataSource
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    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
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        return 5
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    }
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    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
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        let cell = tableView.dequeueReusableCell(withIdentifier: cellReuseIdentifier, for: indexPath)
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        cell.textLabel!.text = "Insert Text #\(indexPath.row)"
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        return cell
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    }
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    // MARK: - UITableViewDelegate
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    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
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        delegate?.insertTextViewController(self, didSelectRowAt: indexPath.row)
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    }
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}
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class AddTextToFreeTextAnnotationAtCaretPositionExample: Example {
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    var pdfController: PDFViewController?
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    override init() {
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        super.init()
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        title = "Add FreeText annotation and insert text at caret position"
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        category = .annotations
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        priority = 100
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    }
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    override func invoke(with delegate: ExampleRunnerDelegate) -> UIViewController? {
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        let document = AssetLoader.temporaryDocument(with: "Example Document")
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        // Add the annotation
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        let freeTextAnnotation = FreeTextAnnotation()
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        freeTextAnnotation.color = .red
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        freeTextAnnotation.contents = "This is a Free Text Annotation"
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        freeTextAnnotation.fontSize = 20
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        // Make the width large to ensure the text fits on one line. This will get trimmed afterwards by the call to `sizeToFit`.
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        freeTextAnnotation.boundingBox = CGRect(x: 200, y: 200, width: 1000000, height: 200)
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        let targetPage: PageIndex = 0
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        freeTextAnnotation.pageIndex = targetPage
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        freeTextAnnotation.sizeToFit()
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        document.add(annotations: [freeTextAnnotation])
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        let controller = PDFViewController(document: document) {
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            $0.overrideClass(FreeTextAccessoryView.self, with: AddTextFreeTextAccessoryView.self)
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        }
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        self.pdfController = controller
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        // Automate selection and entering edit mode
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        DispatchQueue.main.asyncAfter(deadline: .now() + .milliseconds(500)) {
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            // Select annotation and get the view
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            guard let pageView = controller.pageViewForPage(at: controller.pageIndex) else {
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                return
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            }
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            pageView.selectedAnnotations = [freeTextAnnotation]
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            guard let freeTextView = pageView.annotationView(for: freeTextAnnotation) as! FreeTextAnnotationView? else {
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                return
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            }
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            // Begin editing and move caret somewhere to the front.
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            freeTextView.beginEditing()
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            freeTextView.textView?.selectedRange = NSRange(location: 10, length: 0)
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        }
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        return controller
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    }
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}
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private class AddTextFreeTextAccessoryView: FreeTextAccessoryView, InsertTextViewControllerDelegate {
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    lazy var insertTextButton: ToolbarButton = {
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        let button = ToolbarButton()
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        button.length = 50
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        button.accessibilityLabel = "Insert Text"
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        button.setTitle("Insert", for: .normal)
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        button.addTarget(self, action: #selector(self.insertTextTapped), for: .touchUpInside)
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        return button
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    }()
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    @objc func insertTextTapped(sender: FreeTextAccessoryView) {
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        // Second tap should dismiss the controller.
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        if dismissInsertTextViewController(animated: true) {
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            return
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        }
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        // Present controller in a way that it's still a popover on iPhone.
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        let controller = InsertTextViewController()
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        controller.title = "Example Insert Text Controller"
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        controller.delegate = self
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        controller.modalPresentationStyle = .popover
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        let options: [PresentationOption: Any] = [.popoverArrowDirections: UIPopoverArrowDirection.down.rawValue, .nonAdaptive: true, .inNavigationController: true]
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        presentationContext?.actionDelegate.present(controller, options: options, animated: true, sender: sender)
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    }
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    @discardableResult func dismissInsertTextViewController(animated: Bool) -> Bool {
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        return presentationContext!.actionDelegate.dismissViewController(of: InsertTextViewController.self, animated: animated)
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    }
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    // Width changes should dismiss your popover, so ensure to add your hook here.
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    override func dismissPresentedViewControllers(animated: Bool) {
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        super.dismissPresentedViewControllers(animated: animated)
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        dismissInsertTextViewController(animated: animated)
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    }
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    // Adds our custom button.
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    override func buttons(forWidth width: CGFloat) -> [ToolbarButton] {
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        var buttons = super.buttons(forWidth: width)
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        // Insert button before "Clear".
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        let insertionIndex = buttons.firstIndex(of: clearButton) ?? buttons.count - 1
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        buttons.insert(insertTextButton, at: insertionIndex)
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        return buttons
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    }
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    func insertTextViewController(_ controller: InsertTextViewController, didSelectRowAt index: Int) {
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        // First dismiss the `InsertTextViewController`.
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        controller.dismiss(animated: true)
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        // Get current page view. It not be expected for this to fail, but potentially the view hierarchy changed underneath us.
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        guard let pdfController = presentationContext?.pdfController, let pageView = pdfController.pageViewForPage(at: pdfController.pageIndex) else {
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            return
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        }
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        // Find the first free text annotation that is selected.
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        // Nothing to do if no annotation is selected.
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        guard let freeTextAnnotation = pageView.selectedAnnotations.first(where: { $0 is FreeTextAnnotation }) as! FreeTextAnnotation? else {
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            return
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        }
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        // Get the view of the annotation.
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        let freeTextView = pageView.annotationView(for: freeTextAnnotation) as! FreeTextAnnotationView
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        // Get the text view and its selected text range (caret position).
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        // Do nothing if the text view is not in the editing mode or has no caret position (both unexpected).
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        guard let textView = freeTextView.textView, let selectedTextRange = textView.selectedTextRange else {
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            return
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        }
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        // Update text at the selected range.
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        let text = "--NEW TEXT AT CARET POSITION (text index #\(index))--"
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        textView.replace(selectedTextRange, withText: text)
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    }
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}