PDF Collaboration using Swift for iOS

1
//
2
//  Copyright © 2017-2025 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 Instant
9
import PSPDFKit
10
import PSPDFKitUI
11

12
/// This example connects to our public Nutrient Web SDK examples server and downloads documents using Nutrient Instant.
13
/// You can then collaboratively annotate these documents using Instant.
14
/// Each document on the Nutrient Web SDK examples server can be accessed via its URL.
15
///
16
/// The example lets you either create a new collaboration group then share the URL,
17
/// or join an existing collaboration group by entering a URL.
18
/// To speed this up, the URL can be read from a QR code.
19
///
20
/// Other supported clients include:
21
///
22
/// - Nutrient Web SDK examples: https://web-examples.our.services.nutrient-powered.io
23
/// - PDF Viewer for iOS and Android: https://pdfviewer.io
24
/// - Nutrient Catalog example app for Android
25
///
26
/// As is usually the case with Instant, most of the code here deals with communicating with the
27
/// particular server backend (our Web examples server in this case), so is not particularly useful
28
/// as example code. The same applies to the other files in this folder.
29
///
30
/// The code actually interacting with the Instant framework API is in `InstantDocumentViewController.swift`.
31
class InstantExample: Example {
32

33
    override init() {
34
        super.init()
35

36
        title = "Nutrient Instant"
37
        contentDescription = "Downloads a document for collaborative editing."
38
        category = .collaboration
39
        targetDevice = [.vision, .phone, .pad]
40
        priority = 1
41
    }
42

43
    weak var presentingViewController: UIViewController?
44

45
    override func invoke(with delegate: ExampleRunnerDelegate) -> UIViewController? {
46
        let presentingViewController = delegate.currentViewController!
47

48
        // We store the document info once the session is created.
49
        // We will try to find the stored info matching the document identifier for this example if available.
50
        if let docInfoDict = UserDefaults.standard.object(forKey: InstantExampleLastViewedDocumentInfoKey) as? [String: String],
51
           let lastViewDocumentInfo = InstantDocumentInfo(from: docInfoDict) {
52
            // Present the InstantViewController directly using the existing document info extracted from the cache.
53
            presentInstantViewController(for: lastViewDocumentInfo, on: presentingViewController)
54
        } else {
55
            presentNewSession(on: presentingViewController)
56
        }
57

58
        // Hold a reference to the presentingViewController to handle authentication challenges.
59
        self.presentingViewController = presentingViewController
60

61
        return nil
62
    }
63

64
    /// Connects to the Example API Client to get the document info for the current example
65
    /// and then displays that document in a `InstantViewController`.
66
    func presentNewSession(on viewController: UIViewController) {
67
        // Create a `WebExamplesAPIClient` instance using the URL of the client server
68
        // that has the list of documents the particular user can access.
69
        //
70
        // `WebExamplesAPIClient` can make calls to the server to get the document info required
71
        // to connect to a Nutrient Document Engine instance.
72
        //
73
        // For the purpose of this example we are using the Nutrient Web SDK Catalog server.
74
        // In your app, this should be replaced by the URL of your that is interacting with your Nutrient Document Engine.
75
        // See https://www.nutrient.io/guides/ios/instant-synchronization/ for more details.
76
        let apiClient = WebExamplesAPIClient(baseURL: InstantWebExamplesServerURL, delegate: self)
77

78
        let progressHUDItem = StatusHUDItem.indeterminateProgress(withText: "Creating")
79
        progressHUDItem.setHUDStyle(.black)
80

81
        progressHUDItem.push(animated: true, on: viewController.view.window) {
82
            // Asking the Nutrient Web SDK Catalog example server to create a new session
83
            // for the given user and the specified document identifier.
84
            // It should ideally provide a signed JWT (and the Nutrient Document Engine if not already available)
85
            // that can be used by the `InstantClient` to access and download the document for iOS.
86
            apiClient.createNewSession(documentIdentifier: .demoDocument) { result in
87
                DispatchQueue.main.async {
88
                    progressHUDItem.pop(animated: true, completion: nil)
89

90
                    switch result {
91
                    case let .success(documentInfo):
92
                        self.presentInstantViewController(for: documentInfo, on: viewController)
93
                    case .failure(.cancelled):
94
                        break // Do not show the alert if user cancelled the request themselves.
95
                    case let .failure(otherError):
96
                        viewController.showAlert(withTitle: "Couldn’t Get Instant Document Info", message: otherError.localizedDescription)
97
                    }
98
                }
99
            }
100
        }
101
    }
102

103
    private func presentInstantViewController(for instantDocumentInfo: InstantDocumentInfo, on viewController: UIViewController) {
104
        let instantViewController = InstantDocumentViewController(documentInfo: instantDocumentInfo, lastViewedDocumentInfoKey: InstantExampleLastViewedDocumentInfoKey)
105
        instantViewController.title = "Nutrient Instant Example"
106
        let navigationController = UINavigationController(rootViewController: instantViewController)
107
        navigationController.modalPresentationStyle = .fullScreen
108
        viewController.present(navigationController, animated: true)
109
    }
110
}
111

112
extension InstantExample: WebExamplesAPIClientDelegate {
113

114
    func examplesAPIClient(_ apiClient: WebExamplesAPIClient, didReceiveBasicAuthenticationChallenge challenge: URLAuthenticationChallenge, completion: @escaping (URLCredential?) -> Void) {
115
        presentingViewController?.presentBasicAuthPrompt(for: challenge) { username, password in
116
            guard let user = username,
117
                  let pass = password else {
118
                completion(nil)
119
                return
120
            }
121

122
            let urlCredential = URLCredential(user: user, password: pass, persistence: .permanent)
123
            completion(urlCredential)
124
        }
125
    }
126

127
}