Programmatically add a signature to all PDF pages using Swift for iOS

1
//
2
//  Copyright © 2021-2025 PSPDFKit GmbH. All rights reserved.
3
//
4
//  The Nutrient sample applications are licensed with a modified BSD license.
5
//  Please see License for details. This notice may not be removed from this file.
6
//
7

8
import PSPDFKit
9
import PSPDFKitUI
10

11
class SignAllPagesExample: Example {
12
    var status: StatusHUDItem?
13

14
    override init() {
15
        super.init()
16
        title = "Sign All Pages"
17
        contentDescription = "Will add a signature to all pages of a document, optionally flattened."
18
        category = .annotations
19
        priority = 200
20
    }
21

22
    override func invoke(with delegate: ExampleRunnerDelegate?) -> UIViewController? {
23
        guard let baseViewController = delegate?.currentViewController else {
24
            return nil
25
        }
26

27
        // Ask for the annotation username, if needed.
28
        if !UsernameHelper.isDefaultAnnotationUserNameSet {
29
            // We don't use the static helper here because we do not yet have a PDFViewController at this point.
30
            let helper = UsernameHelper()
31
            helper.ask(forDefaultAnnotationUsername: baseViewController, suggestedName: nil) { _ in
32
                self.showSignatureUI(on: baseViewController)
33
            }
34
        } else {
35
            showSignatureUI(on: baseViewController)
36
        }
37

38
        return nil
39
    }
40

41
    func showSignatureUI(on baseViewController: UIViewController) {
42
        // Show the signature controller
43
        let signatureController = SignatureCreationViewController()
44
        signatureController.delegate = self
45

46
        baseViewController.present(signatureController, animated: true)
47
    }
48
}
49

50
extension SignAllPagesExample: SignatureCreationViewControllerDelegate {
51

52
    func signatureCreationViewControllerDidFinish(_ signatureController: SignatureCreationViewController) {
53
        guard let navigationController = signatureController.presentingViewController as? UINavigationController else {
54
            return
55
        }
56

57
        // Create the document.
58
        let document = AssetLoader.writableDocument(for: .annualReport, overrideIfExists: true)
59

60
        // We want to add the signature at the bottom of the page.
61
        for pageIndex in 0..<document.pageCount {
62
            // Check if we have already signed and ignore if so.
63
            let alreadySigned = document.annotationsForPage(at: pageIndex, type: [.ink, .stamp]).contains { annotation in
64
                if let ink = annotation as? InkAnnotation {
65
                    return ink.isSignature
66
                } else if let stamp = annotation as? StampAnnotation {
67
                    return stamp.isSignature
68
                } else {
69
                    return false
70
                }
71
            }
72
            // Not yet signed -> create new annotation.
73
            if !alreadySigned {
74
                self.addAnnotation(from: signatureController, onDocument: document, pageIndex: pageIndex)
75
            }
76
        }
77

78
        // The signature creation view needs to be at the correct size when extracting the
79
        // signature annotations, so don’t dismiss it until after creating the annotations.
80
        signatureController.dismiss(animated: true) {
81
            // Now we could flatten the PDF so that the signature is "burned in".
82
            let flattenAlert = UIAlertController(title: "Flatten Annotations", message: "Flattening will merge the annotations with the page content", preferredStyle: .alert)
83
            flattenAlert.addAction(UIAlertAction(title: "Flatten", style: .destructive, handler: { _ in
84
                let tempURL = FileHelper.temporaryPDFFileURL(prefix: "flattened_signature")
85
                self.status = StatusHUDItem.progress(withText: localizedString("Preparing") + "…")
86
                self.status?.push(animated: true, on: navigationController.view.window)
87
                // Flatten in the background so progress can be shown.
88
                DispatchQueue.global(qos: .default).async {
89
                    let configuration = Processor.Configuration(document: document)!
90
                    configuration.modifyAnnotations(ofTypes: .all, change: .flatten)
91
                    let processor = Processor(configuration: configuration, securityOptions: nil)
92
                    processor.delegate = self
93
                    try? processor.write(toFileURL: tempURL)
94

95
                    DispatchQueue.main.async {
96
                        self.status?.pop(animated: true)
97
                        self.status = nil
98
                        let flattenedDocument = Document(url: tempURL)
99
                        let pdfController = PDFViewController(document: flattenedDocument)
100
                        navigationController.pushViewController(pdfController, animated: true)
101
                    }
102
                }
103
            }))
104
            flattenAlert.addAction(UIAlertAction(title: "Allow Editing", style: .default, handler: { _ in
105
                let pdfController = PDFViewController(document: document)
106
                navigationController.pushViewController(pdfController, animated: true)
107
            }))
108
            navigationController.present(flattenAlert, animated: true)
109
        }
110
    }
111

112
    func signatureCreationViewControllerDidCancel(_ signatureController: SignatureCreationViewController) {
113
        signatureController.dismiss(animated: true)
114
    }
115

116
    func addAnnotation(from signatureController: SignatureCreationViewController, onDocument document: Document, pageIndex: PageIndex) {
117
        guard let pageInfo = document.pageInfoForPage(at: pageIndex),
118
              let annotation = signatureController.signatureAnnotation(forPageWith: pageInfo.size) else {
119
            return
120
        }
121

122
        let margin: CGFloat = 10.0
123
        let maxSize = CGSize(width: 150.0, height: 75.0)
124

125
        // Calculate the size, aspect ratio correct.
126
        let annotationSize = annotation.boundingBox.size
127

128
        let scale: CGFloat = {
129
            let xScale = maxSize.width / annotationSize.width
130
            let yScale = maxSize.height / annotationSize.height
131
            let minScale = min(xScale, yScale)
132
            return minScale > 1.0 ? 1.0 : minScale
133
        }()
134
        let scaledAnnotationSize = CGSize(width: round(annotationSize.width * scale), height: round(annotationSize.height * scale))
135

136
        // Create the annotation.
137
        // Add annotation to bottom right adding additional padding to avoid signature overlapping
138
        // the page number in the PDF. (PDF zero is bottom left)
139
        let pageLabelPadding: CGFloat = 40
140
        annotation.boundingBox = CGRect(x: pageInfo.size.width - scaledAnnotationSize.width - margin, y: margin + pageLabelPadding, width: scaledAnnotationSize.width, height: scaledAnnotationSize.height)
141
        annotation.contents = "Signed on \(DateFormatter.localizedString(from: Date(), dateStyle: .medium, timeStyle: .medium)) by test user."
142
        annotation.pageIndex = pageIndex
143

144
        // Add annotation.
145
        document.add(annotations: [annotation])
146
    }
147
}
148

149
extension SignAllPagesExample: ProcessorDelegate {
150
    func processor(_ processor: Processor, didProcessPage currentPage: UInt, totalPages: UInt) {
151
        status?.progress = CGFloat(currentPage + 1) / CGFloat(totalPages)
152
    }
153
}