Clear All PDF Annotations with a Button in Swift for iOS

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//
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//  Copyright © 2019-2025 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 CustomButtonAnnotationToolbarExample: Example {
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    override init() {
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        super.init()
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        title = "Add a Custom Button to the Annotation Toolbar"
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        contentDescription = "Will add a 'Clear' button to the annotation toolbar that removes all annotations from the visible page."
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        category = .barButtons
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        priority = 210
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    }
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    override func invoke(with delegate: ExampleRunnerDelegate) -> UIViewController {
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        let document = AssetLoader.document(for: .annualReport)
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        let controller = PDFViewController(document: document) {
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            $0.overrideClass(AnnotationToolbar.self, with: AnnotationToolbarWithClearButton.self)
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        }
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        return controller
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    }
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}
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class AnnotationToolbarWithClearButton: AnnotationToolbar, PDFDocumentViewControllerDelegate {
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    var clearAnnotationsButton: ToolbarButton
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    // MARK: - Lifecycle
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    override init(annotationStateManager: AnnotationStateManager) {
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        clearAnnotationsButton = ToolbarButton()
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        clearAnnotationsButton.accessibilityLabel = "Clear"
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        clearAnnotationsButton.image = SDK.imageNamed("trash")!.withRenderingMode(.alwaysTemplate)
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        super.init(annotationStateManager: annotationStateManager)
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        // The biggest challenge here isn't the clear button, but correctly updating the clear button if we actually can clear something or not.
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        let dnc = NotificationCenter.default
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        dnc.addObserver(self, selector: #selector(annotationChangedNotification(_:)), name: NSNotification.Name.PSPDFAnnotationChanged, object: nil)
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        dnc.addObserver(self, selector: #selector(annotationChangedNotification(_:)), name: NSNotification.Name.PSPDFAnnotationsAdded, object: nil)
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        dnc.addObserver(self, selector: #selector(annotationChangedNotification(_:)), name: NSNotification.Name.PSPDFAnnotationsRemoved, object: nil)
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        // Set document view controller delegate to get notified when the page changes.
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        annotationStateManager.pdfController?.documentViewController?.delegate = self
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        // Add clear button
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        clearAnnotationsButton.addTarget(self, action: #selector(clearButtonPressed), for: .touchUpInside)
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        updateClearAnnotationButton()
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        additionalButtons = [clearAnnotationsButton]
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    }
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    // MARK: - Clear Button Action
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    @objc func clearButtonPressed() {
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        guard let pdfController = annotationStateManager.pdfController,
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              let document = pdfController.document else {
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            return
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        }
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        // Iterate over all visible pages and remove all editable annotations.
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        for pageView in pdfController.visiblePageViews {
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            let annotations = document.annotationsForPage(at: pageView.pageIndex, type: editablAnnotationKind)
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            document.remove(annotations: annotations)
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            // Remove any annotation on the page as well (updates views).
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            // Alternatively, you can call `reloadData` on the pdfController.
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            for annotation in annotations {
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                pageView.remove(annotation, options: nil, animated: true)
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            }
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        }
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    }
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    // MARK: - Notifications
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    // If we detect annotation changes, schedule a reload.
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    @objc func annotationChangedNotification(_ notification: Notification?) {
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        // Re-evaluate toolbar button
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        if window != nil {
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            updateClearAnnotationButton()
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        }
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    }
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    override func annotationStateManager(_ manager: AnnotationStateManager, didChangeUndoState undoEnabled: Bool, redoState redoEnabled: Bool) {
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        super.annotationStateManager(manager, didChangeUndoState: undoEnabled, redoState: redoEnabled)
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        updateClearAnnotationButton()
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    }
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    // MARK: - Delegate
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    func documentViewController(_ documentViewController: PDFDocumentViewController, willBeginDisplaying spreadView: PDFSpreadView, forSpreadAt spreadIndex: Int) {
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        updateClearAnnotationButton()
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    }
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    func documentViewController(_ documentViewController: PDFDocumentViewController, didEndDisplaying spreadView: PDFSpreadView, forSpreadAt spreadIndex: Int) {
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        updateClearAnnotationButton()
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    }
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    // MARK: - Private
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    private func updateClearAnnotationButton() {
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        guard let pdfController = annotationStateManager.pdfController else {
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            return
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        }
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        let containsAnnotations = pdfController.visiblePageIndexes.contains { index in
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            let annotations = pdfController.document?.annotationsForPage(at: PageIndex(index), type: editablAnnotationKind) ?? []
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            return !annotations.isEmpty
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        }
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        clearAnnotationsButton.isEnabled = containsAnnotations
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    }
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    private var editablAnnotationKind: Annotation.Kind {
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        var kind = Annotation.Kind.all
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        kind.remove(.link)
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        kind.remove(.widget)
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        return kind
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    }
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}