Persist view settings using Swift for iOS

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//
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//  Copyright © 2019-2026 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 PersistViewSettingsExample: Example, PDFViewControllerDelegate {
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    let pageTransition = "pageTransition"
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    let pageMode = "pageMode"
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    let scrollDirection = "scrollDirection"
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    let spreadFitting = "spreadFitting"
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    override init() {
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        super.init()
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        contentDescription = "Shows how to persist PDFSettingsViewController options using UserDefaults."
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        category = .controllerCustomization
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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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        let controller = PDFViewController(document: document, delegate: self) {
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            // Configure the `PDFSettingsViewController`'s options.
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            $0.settingsOptions = [.pageTransition, .pageMode, .scrollDirection, .spreadFitting]
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            // Restore the settings from the user defaults.
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            let defaults = UserDefaults.standard
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            $0.pageTransition = PageTransition(rawValue: UInt(defaults.integer(forKey: self.pageTransition)))!
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            $0.pageMode = PageMode(rawValue: UInt(defaults.integer(forKey: self.pageMode)))!
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            $0.scrollDirection = ScrollDirection(rawValue: UInt(defaults.integer(forKey: self.scrollDirection)))!
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            $0.spreadFitting = PDFConfiguration.SpreadFitting(rawValue: defaults.integer(forKey: self.spreadFitting))!
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        }
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        // Configure the left bar button items.
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        controller.navigationItem.setLeftBarButtonItems([controller.settingsButtonItem], animated: false)
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        controller.navigationItem.leftItemsSupplementBackButton = true
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        return controller
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    }
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    // MARK: - PDFViewControllerDelegate
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    func pdfViewControllerDidDismiss(_ pdfController: PDFViewController) {
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        // Persist the settings options in the user defaults.
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        let defaults = UserDefaults.standard
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        defaults.set(pdfController.configuration.pageTransition.rawValue, forKey: pageTransition)
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        defaults.set(pdfController.configuration.pageMode.rawValue, forKey: pageMode)
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        defaults.set(pdfController.configuration.scrollDirection.rawValue, forKey: scrollDirection)
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        defaults.set(pdfController.configuration.spreadFitting.rawValue, forKey: spreadFitting)
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    }
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}