Customize Blend Modes in Stamp Annotations 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 AnnotationInspectorBlendModeStampExample: Example {
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    override init() {
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        super.init()
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        title = "Configure the annotation Inspector to set Blend Mode for stamp annotations"
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        contentDescription = "Shows how to customize the annotation Inspector to set Blend Mode for vector stamp annotations."
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        category = .annotations
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        priority = 203
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    }
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    override func invoke(with delegate: ExampleRunnerDelegate) -> UIViewController {
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        let document = AssetLoader.writableDocument(for: .welcome, overrideIfExists: false)
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        document.annotationSaveMode = .embedded
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        // Add stamp annotation if there isn't one already.
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        let pageIndex: PageIndex = 0
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        let stamps = document.annotationsForPage(at: pageIndex, type: .stamp)
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        if stamps.isEmpty {
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            let logoURL = AssetLoader.assetURL(for: "PSPDFKit Logo.pdf")
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            let stampAnnotation = StampAnnotation()
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            stampAnnotation.boundingBox = CGRect(x: 180.0, y: 150.0, width: 444.0, height: 500.0)
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            stampAnnotation.appearanceStreamGenerator = FileAppearanceStreamGenerator(fileURL: logoURL)
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            stampAnnotation.pageIndex = pageIndex
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            document.add(annotations: [stampAnnotation])
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        }
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        let controller = BlendModeInspectorForStampsViewController(document: document) {
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            // Do not show color presets.
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            var typesShowingColorPresets = $0.typesShowingColorPresets
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            typesShowingColorPresets.remove(.stamp)
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            $0.typesShowingColorPresets = typesShowingColorPresets
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            // Configure the properties for stamp annotations to show the blend mode setting in the annotation Inspector.
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            var properties = $0.propertiesForAnnotations
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            properties[.stamp] = [[AnnotationStyle.Key.blendMode]]
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            $0.propertiesForAnnotations = properties
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        }
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        return controller
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    }
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}
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private class BlendModeInspectorForStampsViewController: PDFViewController {
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    override func viewDidAppear(_ animated: Bool) {
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        super.viewDidAppear(animated)
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        // Select the stamp annotation to show the Inspector menu.
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        let pageView = self.pageViewForPage(at: 0)
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        guard let stampAnnotation = self.document?.annotationsForPage(at: pageIndex, type: .stamp).first else { return }
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        pageView?.select(annotations: [stampAnnotation], presentMenu: true, animated: true)
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    }
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}