Autosave PDF annotation changes in Swift for iOS

1
//
2
//  Copyright © 2019-2026 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
// This class will ask the user as soon as the first annotation has been added/modified where the annotation should be saved, and optionally copies the file to a new location.
12

13
class AnnotationSaveAsForAnnotationEditingExample: Example {
14
    override init() {
15
        super.init()
16
        title = "Save as... for annotation editing"
17
        contentDescription = "Adds an alert after detecting annotation writes to define a new save location."
18
        category = .annotations
19
        priority = 100
20
    }
21

22
    override func invoke(with delegate: ExampleRunnerDelegate) -> UIViewController? {
23
        let document = AssetLoader.writableDocument(for: .annualReport, overrideIfExists: false)
24
        return SaveAsPDFViewController(document: document)
25
    }
26
}
27

28
// MARK: PDFViewController
29

30
private class SaveAsPDFViewController: PDFViewController {
31
     var hasUserBeenAskedAboutSaveLocation = false
32
     private var observer: Any?
33

34
    override func commonInit(with document: Document?, configuration: PDFConfiguration) {
35
        super.commonInit(with: document, configuration: configuration)
36

37
        navigationItem.rightBarButtonItems = [thumbnailsButtonItem, annotationButtonItem]
38

39
        let closeButton = UIBarButtonItem(barButtonSystemItem: .close, target: self, action: #selector(closeButtonTapped(_:)))
40
        navigationItem.leftBarButtonItems = [closeButton]
41

42
        NotificationCenter.default.addObserver(self, selector: #selector(annotationChangedNotification), name: .PSPDFAnnotationChanged, object: nil)
43
        NotificationCenter.default.addObserver(self, selector: #selector(annotationAddedOrRemovedNotification), name: .PSPDFAnnotationsAdded, object: nil)
44
        NotificationCenter.default.addObserver(self, selector: #selector(annotationAddedOrRemovedNotification), name: .PSPDFAnnotationsRemoved, object: nil)
45
    }
46

47
    deinit {
48
    // Clear document cache, so we don't get annotation-artefacts when loading the doc again.
49
        SDK.shared.cache.remove(for: document)
50
    }
51

52
    // MARK: Private
53
    @objc private func closeButtonTapped(_ sender: UIBarButtonItem) {
54
        annotationStateManager.state = nil  // Commit any annotations
55
        navigationController?.popViewController(animated: true)
56
    }
57

58
    @objc private func annotationChangedNotification(_ notification: Notification) {
59
        guard let notificationObject = notification.object as? Annotation else { return }
60
        processChangeForAnnotation(annotation: notificationObject)
61
    }
62

63
    @objc private func annotationAddedOrRemovedNotification(_ notification: NSNotification) {
64
        guard let notificationObject = notification.object as? [Annotation] else { return }
65
        for annotation in notificationObject {
66
            processChangeForAnnotation(annotation: annotation)
67
        }
68
    }
69

70
    private func processChangeForAnnotation(annotation: Annotation) {
71
        if annotation.document == document {
72
            self.askUserAboutSaveLocationIfNeeded()
73
        }
74
    }
75

76
    // Mark - Document Copying Logic
77

78
    // This code assumes that the PDF location itself is writeable, and will fail for documents in the bundle folder.
79
    private func askUserAboutSaveLocationIfNeeded() {
80
        // Make sure the alert gets displayed only once per session
81
        if hasUserBeenAskedAboutSaveLocation {
82
            return
83
        }
84
        hasUserBeenAskedAboutSaveLocation = true
85

86
        let alertController = UIAlertController(title: nil, message: "Would you like to save annotations into the current file, or create a copy to save the annotation changes?", preferredStyle: .alert)
87
        alertController.addAction(UIAlertAction(title: "Save to This File", style: .destructive))
88
        alertController.addAction(UIAlertAction(title: "Save as Copy", style: .default, handler: { _ in
89
            self.replaceDocumentWithCopy()
90
        }))
91
        present(alertController, animated: true, completion: nil)
92
    }
93

94
    private func replaceDocumentWithCopy() {
95
        guard let documentURL = document?.fileURL else { return }
96

97
        let newURL = adjustedFileURLForDocumentURL(documentURL)
98

99
        do {
100
            try FileManager.default.copyItem(at: documentURL, to: newURL)
101
            // Since the annotation has already been edited, we copy the file *before* it will be saved
102
            // then save the current state and switch out the documents.
103
        } catch {
104
            print("Failed to copy file to \(newURL.path): \(error.localizedDescription)")
105
            return
106
        }
107

108
        do {
109
            try document?.save()
110
        } catch {
111
            print("Failed to save document: \(error.localizedDescription)")
112
        }
113

114
        let tmpURL = newURL.appendingPathExtension("temp")
115
        do {
116
            try FileManager.default.moveItem(at: documentURL, to: tmpURL)
117
        } catch {
118
            print("Failed to move file: \(error.localizedDescription)")
119
            return
120
        }
121

122
        do {
123
            try FileManager.default.moveItem(at: newURL, to: documentURL)
124
        } catch {
125
            print("Failed to move file: \(error.localizedDescription)")
126
            return
127
        }
128

129
        do {
130
            try FileManager.default.moveItem(at: tmpURL, to: newURL)
131
        } catch {
132
            print("Failed to move file: \(error.localizedDescription)")
133
            return
134
        }
135

136
        // Finally update the fileURL, this will clear the current document cache.
137
        let newDocument = Document(url: newURL)
138
        newDocument.title = document?.title // Preserve the title
139

140
        // Preserve annotation selection
141
        guard var pageView: PDFPageView = pageViewForPage(at: pageIndex) else { return }
142
        guard let selectedAnnotations = pageView.selectedAnnotations else { return }
143

144
        document = newDocument
145

146
        // Restore selection
147
        pageView = pageViewForPage(at: pageIndex)!
148
        var newSelectedAnnotations: [Annotation] = []
149
        for annotation in newDocument.annotationsForPage(at: pageIndex, type: .all) {
150
            for selectedAnnotation in selectedAnnotations where annotation.name == selectedAnnotation.name {
151
                newSelectedAnnotations.append(annotation)
152
            }
153
        }
154

155
        // To re-show the popover, we need to wait until the alert view disappears.
156
        DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 0.3, execute: {
157
            pageView.select(annotations: newSelectedAnnotations, presentMenu: true, animated: true)
158
        })
159
    }
160

161
    /// Appends `_annotated` to the file basename. Also appends an incrementing integer if a file with a matching name already exists.
162
    ///
163
    /// For example, `Document.pdf` would change to `Document_annotated.pdf`.
164
    /// If `Document_annotated.pdf` already exists then `Document_annotated1.pdf` would be generated instead. Then `Document_annotated2.pdf` etc.
165
    private func adjustedFileURLForDocumentURL(_ documentURL: URL) -> URL {
166
        var appendFileCount = 0
167
        var newPath: NSString
168

169
        repeat {
170
            newPath = documentURL.path as NSString
171
            let appendSuffix = "_annotated\(appendFileCount == 0 ? "" : "\(appendFileCount)").pdf"
172
            if newPath.lowercased.hasSuffix(".pdf") {
173
                newPath = newPath.replacingOccurrences(of: ".pdf", with: appendSuffix, options: .caseInsensitive, range: NSRange(location: newPath.length - 4, length: 4)) as NSString
174
            } else {
175
                newPath = newPath.appending(appendSuffix) as NSString
176
            }
177
            appendFileCount += 1
178
        } while FileManager.default.fileExists(atPath: newPath as String)
179

180
        return NSURL.fileURL(withPath: newPath as String)
181
    }
182
}