PDF text redaction using regex in Swift for iOS

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//
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//  Copyright © 2021-2026 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 RedactTextUsingRegexExample: Example {
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    override init() {
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        super.init()
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        title = "Redact Text Using Regular Expressions"
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        contentDescription = "Shows how to redact URLs using a regex pattern."
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        category = .documentProcessing
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        priority = 16
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    }
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    override func invoke(with delegate: ExampleRunnerDelegate) -> UIViewController? {
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        let document = AssetLoader.document(for: .web)
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        let status = StatusHUDItem.indeterminateProgress(withText: "Processing...")
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        status.push(animated: true, on: delegate.currentViewController?.view.window)
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        // The regex pattern for URLs.
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        let urlPattern = #"[-a-zA-Z0-9@:%._\+~#=]{1,256}\.[a-zA-Z0-9()]{1,6}\b([-a-zA-Z0-9()@:%_\+.~#?&//=]*)"#
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        let urlRegularExpression = try! NSRegularExpression(pattern: urlPattern)
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        // Loop through all the pages in the document to find URLs.
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        // In production we recommend doing this on a utility queue.
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        for pageIndex in 0..<document.pageCount {
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            if let textParser = document.textParserForPage(at: pageIndex) {
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                textParser.words.forEach { word in
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                    let wordString = word.stringValue
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                    let range = NSRange(wordString.startIndex..<wordString.endIndex, in: wordString)
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                    // Redact all the words that match the regex.
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                    let isValidURL = urlRegularExpression.numberOfMatches(in: wordString, options: [], range: range) > 0
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                    if isValidURL {
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                        let redaction = self.createRedactionAnnotationFor(word: word, pageIndex: pageIndex)
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                        document.add(annotations: [redaction])
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                    }
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                }
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            }
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        }
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        DispatchQueue.global(qos: .default).async {
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            // Use Processor to create the newly redacted document.
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            let processorConfiguration = Processor.Configuration(document: document)!
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            processorConfiguration.applyRedactions()
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            let redactedDocumentURL = FileHelper.temporaryPDFFileURL(prefix: "redacted")
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            let processor = Processor(configuration: processorConfiguration, securityOptions: nil)
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            try? processor.write(toFileURL: redactedDocumentURL)
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            DispatchQueue.main.async {
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                status.pop(animated: true)
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                // Instantiate the redacted document and present it.
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                let redactedDocument = Document(url: redactedDocumentURL)
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                let pdfController = PDFViewController(document: redactedDocument)
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                delegate.currentViewController!.navigationController?.pushViewController(pdfController, animated: true)
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            }
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        }
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        return nil
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    }
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    // MARK: Private
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    private func createRedactionAnnotationFor(word: Word, pageIndex: PageIndex) -> RedactionAnnotation {
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        let redactionRect = word.frame
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        let redaction = RedactionAnnotation()
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        redaction.boundingBox = redactionRect
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        redaction.rects = [redactionRect]
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        redaction.color = .orange
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        redaction.fillColor = .black
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        redaction.overlayText = "REDACTED"
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        redaction.pageIndex = pageIndex
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        return redaction
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    }
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}