Custom PDF bookmark provider in 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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class CustomBookmarkProviderExample: Example {
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    override init() {
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        super.init()
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        title = "Custom Bookmark Provider"
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        contentDescription = "Shows how to use a custom bookmark provider using a plist file"
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        category = .subclassing
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        priority = 250
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    }
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    override func invoke(with delegate: ExampleRunnerDelegate) -> UIViewController {
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        let document = AssetLoader.writableDocument(for: .annualReport, overrideIfExists: false)
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        document.bookmarkManager?.provider = [BookmarkParser()]
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        let controller = PDFViewController(document: document) {
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            $0.bookmarkSortOrder = .custom
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        }
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        controller.navigationItem.setRightBarButtonItems([controller.thumbnailsButtonItem, controller.outlineButtonItem, controller.searchButtonItem, controller.bookmarkButtonItem], for: .document, animated: false)
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        return controller
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    }
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}
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class BookmarkParser: NSObject, BookmarkProvider {
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    struct CustomBookmark: Codable {
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        let identifier: String
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        let pageIndex: PageIndex
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        let name: String
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        let sortKey: Int
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        private enum CodingKeys: String, CodingKey {
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            case identifier
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            case pageIndex
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            case name
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            case sortKey
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        }
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        init(bookmark: Bookmark) {
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            self.identifier = bookmark.identifier
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            self.pageIndex = bookmark.pageIndex
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            self.name = bookmark.name?.replacingOccurrences(of: "\"", with: "'") ?? String()
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            if let sortKey = bookmark.sortKey {
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                self.sortKey = sortKey.intValue
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            } else {
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                self.sortKey = 0
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            }
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        }
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        func encode(to encoder: Encoder) throws {
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            var container = encoder.container(keyedBy: CodingKeys.self)
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            try container.encode(identifier, forKey: .identifier)
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            try container.encode(pageIndex, forKey: .pageIndex)
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            try container.encode(name, forKey: .name)
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            try container.encode(sortKey, forKey: .sortKey)
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        }
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        init(from decoder: Decoder) throws {
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            let values = try decoder.container(keyedBy: CodingKeys.self)
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            identifier = try values.decode(String.self, forKey: .identifier)
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            pageIndex = try values.decode(PageIndex.self, forKey: .pageIndex)
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            name = try values.decode(String.self, forKey: .name)
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            sortKey = try values.decode(Int.self, forKey: .sortKey)
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        }
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    }
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    var bookmarks: [Bookmark] {
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        return self.bookmarkData
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    }
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    var bookmarkData: [Bookmark]
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    override init() {
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        self.bookmarkData = BookmarkParser.bookmarkDataFromFile()
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        super.init()
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    }
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    func add(_ bookmark: Bookmark) -> Bool {
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        print("Add Bookmark: \(bookmark)")
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        let index = bookmarkData.firstIndex(of: bookmark)
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        if index == nil || index == NSNotFound {
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            bookmarkData.append(bookmark)
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        } else {
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            bookmarkData[index!] = bookmark
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        }
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        return true
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    }
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    func remove(_ bookmark: Bookmark) -> Bool {
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        print("Remove Bookmark: \(bookmark)")
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        if bookmarkData.contains(bookmark) {
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            while let elementIndex = bookmarkData.firstIndex(of: bookmark) {
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                bookmarkData.remove(at: elementIndex)
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            }
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            return true
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        } else {
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            return false
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        }
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    }
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    func save() {
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        print("Save bookmarks.")
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        let customBookmarks = bookmarkData.map({ return CustomBookmark(bookmark: $0) })
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        let jsonData = try? PropertyListEncoder().encode(customBookmarks)
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        try? jsonData?.write(to: BookmarkParser.bookmarkURL()!, options: Data.WritingOptions.atomic)
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    }
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    // MARK: Helpers
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    class func bookmarkURL() -> URL? {
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        let applicationSupport = try? FileManager.default.url(for: .applicationSupportDirectory, in: .userDomainMask, appropriateFor: nil, create: true)
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        let fileURL = applicationSupport?.appendingPathComponent("customBookmarksProvider").appendingPathExtension("plist")
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        return fileURL
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    }
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    class func bookmarkDataFromFile() -> [Bookmark] {
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        var bookmarkData = [Bookmark]()
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        guard let jsonData = try? Data(contentsOf: BookmarkParser.bookmarkURL()!) else {
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            return bookmarkData
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        }
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        let customBookmark: [CustomBookmark] = try! PropertyListDecoder().decode(Array.self, from: jsonData)
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        bookmarkData = customBookmark.map({
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            let identifier = $0.identifier
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            let pageIndex = $0.pageIndex
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            let name = $0.name
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            let sortKey = NSNumber(value: $0.sortKey)
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            let action = GoToAction(pageIndex: PageIndex(pageIndex))
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            return Bookmark(identifier: identifier, action: action, name: name, sortKey: sortKey)
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        })
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        return bookmarkData
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    }
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}