Customize Pencil Interactions on PDF using Swift for iOS

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//
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//  Copyright © 2018-2025 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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#if !os(visionOS)
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class CustomPencilInteractionExample: Example {
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    override init() {
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        super.init()
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        title = "Custom Pencil Interaction Action"
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        contentDescription = "Performs a custom action in response to UIPencilInteraction."
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        category = .annotations
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    }
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    override func invoke(with delegate: ExampleRunnerDelegate) -> UIViewController {
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        let document = AssetLoader.document(for: .welcome)
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        return CustomPencilInteractionViewController(document: document)
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    }
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    class CustomPencilInteractionViewController: PDFViewController, UIPencilInteractionDelegate {
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        override func viewDidLoad() {
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            super.viewDidLoad()
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            // Disable Nutrient’s default Pencil interaction handling by removing the interaction.
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            // Setting the `isEnabled` property will not work because Nutrient may set this property internally.
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            let builtInPencilInteraction = annotationStateManager.pencilInteraction
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            builtInPencilInteraction.view?.removeInteraction(builtInPencilInteraction)
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            // Add the custom interaction.
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            let customPencilInteraction = UIPencilInteraction()
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            customPencilInteraction.delegate = self
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            view.addInteraction(customPencilInteraction)
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        }
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        func pencilInteractionDidTap(_ interaction: UIPencilInteraction) {
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            let alert = UIAlertController(title: "Apple Pencil Tap!", message: nil, preferredStyle: .alert)
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            alert.addAction(UIAlertAction(title: "OK", style: .cancel))
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            present(alert, animated: true, completion: nil)
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        }
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    }
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}
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#endif