Learn how to build an iOS application that can verify an mDoc presented via a proximity workflow

Create a new project

Please follow the detailed instructions to Create a new Xcode Project  and add your organization’s identifier.

Unzip the dependencies file

1. Unzip the MobileCredentialVerifierSDK-*version*.xcframework.zip file.
2. Drag the MobileCredentialVerifierSDK-*version*.xcframework folder into your project.
3. Configure MobileCredentialVerifierSDK.xcframework to Embed & sign .

See Add existing files and folders  for detailed instructions.

This should result in the the following framework being added to your project:

Add Bluetooth permissions

The SDK requires access to the mobile device Bluetooth capabilities as part of the proximity presentation workflow. Configure these permissions  in the Info tab of the Application target:

Run the application

Select Run and make sure the application launches with a “Hello, world!” text in the middle of the display, as shown in the following image:

Create the application structure

1. Open the ContentView file in your new project and replace any existing code with the following:

   Swift

   import SwiftUI
   // Initialize SDK - Step 2.1: import MobileCredentialVerifierSDK
    
   struct ContentView: View {
       @ObservedObject var viewModel: VerifierViewModel = VerifierViewModel()
    
       var body: some View {
           NavigationStack(path: $viewModel.navigationPath) {
               VStack {
                   Button("Certificate Management") {
                       viewModel.navigationPath.append(NavigationState.certificateManagement)
                   }
                   .padding()
    
                   Button("Scan QR Code") {
                       viewModel.navigationPath.append(NavigationState.scanQRCode)
                   }
                   .padding()
    
                   Button("View Response") {
                       viewModel.navigationPath.append(NavigationState.viewResponse)
                   }
                   .padding()
               }
               .navigationDestination(for: NavigationState.self) { destination in
                   switch destination {
                   case .certificateManagement:
                       certificateManagementView
                   case .scanQRCode:
                       codeScannerView
                   case .viewResponse:
                       presentationResponseView
                   }
               }
           }
       }
    
       // MARK: Verification Views
    
    
       var codeScannerView: some View {
       // Verify mDocs - Step 2.4: Create QRScannerView
           EmptyView()
       }
       // Manage Certificates - Step 1.2: Create CertificateManagementView
       var certificateManagementView: some View {
           EmptyView()
       }
       var presentationResponseView: some View {
       // Verify mDocs - Step 4.2: Create PresentationResponseView
           EmptyView()
       }
   }
    
   // MARK: VerifierViewModel
    
   final class VerifierViewModel: ObservableObject {
       @Published var navigationPath = NavigationPath()
       // Initialize SDK - Step 2.2: Add MobileCredentialVerifier var
    
       // Verify mDocs - Step 1.1: Create MobileCredentialRequest instance
    
       // Verify mDocs - Step 1.2: Create receivedDocuments variable
    
       // Initialize SDK - Step 2.3: Initialize the SDK
   }
    
   // MARK: Proximity Presentation
   extension VerifierViewModel {
       func setupProximityPresentationSession(_ deviceEngagementString: String) {
       // Verify mDocs - Step 3.2: Create setupProximityPresentationSession
           print("This method will use qr code string do setup proximity session")
       }
       func sendDeviceRequest() {
       // Verify mDocs - Step 3.3: Create sendDeviceRequest function
           print("This method will send preconfigured device request to holder app")
       }
   }
    
   // Verify mDocs - Step 3.1: Extend VerifierViewModel class
    
    
   // MARK: - Navigation
   enum NavigationState: Hashable {
       case certificateManagement
       case scanQRCode
       case viewResponse
   }

Initialize the MobileCredentialVerifier class

1. Add the following code after the // Initialize SDK - Step 2.1: Import MobileCredentialVerifierSDK comment to import MobileCredentialVerifierSDK and gain access to the SDK’s capabilities:

   Swift

   import MobileCredentialVerifierSDK

2. Add the following code after the // Initialize SDK - Step 2.2: Add MobileCredentialVerifier var comment to create a variable that holds the mobileCredentialVerifier instance:

   Swift

       var mobileCredentialVerifier: MobileCredentialVerifier

3. Add the following code after the // Initialize SDK - Step 2.3: Initialize the SDK comment to assign a shared instance of the class to our mobileCredentialVerifier variable and initialize the SDK:

   Swift

       init() {
           do {
               mobileCredentialVerifier = MobileCredentialVerifier.shared
               try mobileCredentialVerifier.initialize()
           } catch {
               print(error.localizedDescription)
           }
       }

4. Run  the app to ensure it compiles successfully.

Once the app launches you will see a screen with three buttons, each leading to an empty view. In the following steps, you will implement proximity presentation functionalities into these views.

Create the Certificate Management view

1. Create a new file named CertificateManagementView and paste the following code in it:

   Swift

   import SwiftUI
   import MobileCredentialVerifierSDK
    
   struct CertificateManagementView: View {
       @ObservedObject var viewModel = CertificateManagementViewModel()
       @State var certificateString = ""
    
       var body: some View {
           Form {
               Section(
                   header: Text("IACA Certificate").font(.headline),
                   footer: HStack {
                       Spacer()
                       Button("Add") {
                           viewModel.addCertificate(certificateString)
                       }
                       Spacer().frame(width: 30)
                       Button("Clear") {
                           certificateString = ""
                       }
                       .foregroundColor(.red)
                       .contentShape(Rectangle())
                       .frame(alignment: .trailing)
                   }
               ) {
                   TextField("IACA certificate string", text: $certificateString)
               }
    
               Section(
                   header: Text("Stored Certificates").font(.headline)
               ) {
                   certificateListView
               }
           }
           .navigationBarTitle("Certificate Setting")
           .onAppear {
               viewModel.getCertificates()
           }
       }
    
       // MARK: Certificate Management Views
       var certificateListView: some View {
       // Manage Certificates - Step 2.3: Display retrieved certificates
           EmptyView()
       }
   }
    
   final class CertificateManagementViewModel: ObservableObject {
       // Manage Certificates - Step 2.1: Add certificates and verifier variable
    
       func getCertificates() {
       // Manage Certificates - Step 2.2: Create getCertificates function
           print("This will fetch certificates from storage")
       }
    
       func addCertificate(_ certificate: String) {
       // Manage Certificates - Step 2.4: Create addCertificate function
           print("This will add certificate to storage and get a new list of certificates")
       }
       func removeCertificate(_ certificateID: String) {
       // Manage Certificates - Step 2.5: Create removeCertificate function
           print("This will remove certificates from storage and get a new list of certificates")
       }
   }
    

The CertificateManagementView file provides a basic user interface for displaying a list of certificates and controls for managing certificate storage. The CertificateManagementViewModel class contains the logic for adding, retrieving, and removing certificates.

2. Return to the ContentView file and replace the EmptyView() under the // Manage certificates - Step 1.2: Create CertificateManagementView comment with a reference to the new view you created in the previous step:

   Swift

       CertificateManagementView()

3. Run  the app and select the Certificate Management button. You should see a result similar to the following:

As the user selects the Certificate Management button they are navigated to the new CertificateManagement view where they can see controls that would enable them to add, view and remove certificates. We will build these capabilities into the controls in the next step.

Add Certificate Management functionalities

Currently our CertificateManagementView view has no functionalities. Let’s fix this by adding the capabilities to add, view and remove certificates.

1. Open the CertificateManagementView file and add the following code under the // Manage Certificates - Step 2.1: Add certificates variable comment to add a new certificates variable that will hold the certificates added to the application and a reference to a shared instance of MobileCredentialVerifier:

   CertificateManagementView

       @Published var certificates: [TrustedCertificate] = []
       let mobileCredentialVerifier = MobileCredentialVerifier.shared

2. Replace the print statement under the // Manage Certificates - Step 2.2: Create getCertificates function comment to call the SDK getTrustedIssuerCertificates , retrieve all certificates and display them to the user:

   CertificateManagementView

           do {
               let fetchedCertificates = try mobileCredentialVerifier.getTrustedIssuerCertificates()
               certificates = fetchedCertificates
           } catch {
               print(error.localizedDescription)
           }

3. Replace the EmptyView() under the // Manage Certificates - Step 2.3: Display retrieved certificates comment to iterate over retrieved certificates and display them to the user:

   CertificateManagementView

       ForEach(viewModel.certificates, id: \.id) { certificate in
           Text("\(certificate.pem)")
               .frame(maxHeight: 100)
               .swipeActions(edge: .trailing) {
                   Button(role:. destructive) {
                       viewModel.removeCertificate(certificate.id)
                   } label: {
                       Image(systemName: "trash")
                   }
               }
       }

4. Replace the print statement under the // Manage Certificates - Step 2.4: Create addCertificate function comment to call the SDK addTrustedIssuerCertificates , accept a string parameter and use it to add a new certificate:

   CertificateManagementView

       Task { @MainActor in
           do {
               _ = try await mobileCredentialVerifier.addTrustedIssuerCertificates(certificates: [certificate])
               self.getCertificates()
           }
           catch {
               print(error.localizedDescription)
           }
       }

5. Replace the print statement under the // Manage Certificates - Step 2.5: Create removeCertificate function to call the SDK deleteTrustedIssuerCertificate  and remove a selected certificate:

   CertificateManagementView

       do {
           try mobileCredentialVerifier.deleteTrustedIssuerCertificate(certificateId: certificateID)
           // Refresh the certificates list after deletion
           self.getCertificates()
       } catch {
           print(error.localizedDescription)
       }

6. Run  the app and perform the following instructions:

   1. Select the Manage Certificates button.

   2. Copy and paste the following text into the IACA Certificate text box.

      MIICYzCCAgmgAwIBAgIKXhjLoCkLWBxREDAKBggqhkjOPQQDAjA4MQswCQYDVQQG
      EwJBVTEpMCcGA1UEAwwgbW9udGNsaWZmLWRtdi5tYXR0cmxhYnMuY29tIElBQ0Ew
      HhcNMjQwMTE4MjMxNDE4WhcNMzQwMTE1MjMxNDE4WjA4MQswCQYDVQQGEwJBVTEp
      MCcGA1UEAwwgbW9udGNsaWZmLWRtdi5tYXR0cmxhYnMuY29tIElBQ0EwWTATBgcq
      hkjOPQIBBggqhkjOPQMBBwNCAASBnqobOh8baMW7mpSZaQMawj6wgM5e5nPd6HXp
      dB8eUVPlCMKribQ7XiiLU96rib/yQLH2k1CUeZmEjxoEi42xo4H6MIH3MBIGA1Ud
      EwEB/wQIMAYBAf8CAQAwDgYDVR0PAQH/BAQDAgEGMB0GA1UdDgQWBBRFZwEOI9yq
      232NG+OzNQzFKa/LxDAuBgNVHRIEJzAlhiNodHRwczovL21vbnRjbGlmZi1kbXYu
      bWF0dHJsYWJzLmNvbTCBgQYDVR0fBHoweDB2oHSgcoZwaHR0cHM6Ly9tb250Y2xp
      ZmYtZG12LnZpaS5hdTAxLm1hdHRyLmdsb2JhbC92Mi9jcmVkZW50aWFscy9tb2Jp
      bGUvaWFjYXMvMjk0YmExYmMtOTFhMS00MjJmLThhMTctY2IwODU0NWY0ODYwL2Ny
      bDAKBggqhkjOPQQDAgNIADBFAiAlZYQP95lGzVJfCykhcpCzpQ2LWE/AbjTGkcGI
      SNsu7gIhAJfP54a2hXz4YiQN4qJERlORjyL1Ru9M0/dtQppohFm6

3. Select the Add button. The new certificate should appear in the STORED CERTIFICATES area.

4. Swipe left across the new certificate and select the Delete icon to remove it.

You should get a result similar to the following:

1. When the user selects the Certificate Management button they are navigated to the CertificateManagement view.
2. When the user adds the text and selects the Add button a new certificate is added and displayed in the STORED CERTIFICATES area.
3. When the user swipes left and selects the Delete icon the certificate is removed.

Create a presentation request

As a verifier, you can select what information you request for verification. Our application implements this by creating a MobileCredentialRequest  instance to define the required information, and a new variable to hold the response from the wallet application.

1. Open the ContentView file and add the following code under the // Verify mDocs - Step 1.1: Create MobileCredentialRequest instance comment to define what information to request from the wallet application user:

   Swift

       let mobileCredentialRequest = MobileCredentialRequest(
           docType: "org.iso.18013.5.1.mDL",
           namespaces: [
               "org.iso.18013.5.1":  [
                   "family_name": false,
                   "given_name": false,
                   "birth_date": false
               ]
           ]
       )

   This object details:

   • The requested credential type (e.g. org.iso.18013.5.1.mDL).
   • The claims required for verification (e.g. family_name).
   • The requested namespace (e.g. org.iso.18013.5.1).
   • Whether or not the verifier intends to persist the claim value (true/false).

   For the verification to be successful, the presented credential must include the referenced claim against the specific namespace defined in the request. Our example requests the birth_date under the org.iso.18013.5.1 namespace. If a wallet responds to this request with a credential that includes a birth_date but rather under the org.iso.18013.5.1.US namespace, the claim will not be verified.

2. Add the following code under the Verify mDocs - Step 1.2: Create receivedDocuments variable comment to create a new receivedDocuments variable that will hold the response from the wallet application:

   Swift

       @Published var receivedDocuments: [MobileCredentialPresentation] = []

Your application now has an existing credential request to share, and a variable to hold any incoming responses. In the next step we will build the capabilities to send this request and handle the response.

Scan and process a QR code

As defined in ISO/IEC 18130-5:2021, a proximity presentation workflow is always initiated by the holder (wallet application user), who must create a QR code for the verifier to scan in order to initiate the device engagement phase.

This means that your verifier application must be able to scan and process this QR code. For ease of implementation, we will use a third party framework to achieve this.

1. Add camera usage permissions  to the app target:

2. Add the CodeScanner  library via Swift Package Manager .

3. Create a new swift file  named QRScannerView and add the following code into it to implement the QR scanning capability:

   Swift

   import SwiftUI
   import CodeScanner
    
   struct QRScannerView: View {
    
       private let completionHandler: (String) -> Void
    
       init(completion: @escaping (String) -> Void) {
           completionHandler = completion
       }
    
       var body: some View {
           CodeScannerView(codeTypes: [.qr]) { result in
               switch result {
               case .failure(let error):
                   print(error.localizedDescription)
               case .success(let result):
                   print(result.string)
                   completionHandler(result.string)
               }
           }
       }
   }

4. Back in the ContentView file, replace the EmptyView() under the // Verify mDocs - Step 2.4: Create QRScannerView comment with the following code to create a new app view that the user will use to scan a QR code:

   Swift

       QRScannerView(
           completion: { string in
               viewModel.setupProximityPresentationSession(string)
           }
       )

5. Run  the app and select the Scan QR Code button. You should be navigated to the new QRScannerView where you can use the camera to scan a QR code.

Next we will build the logic that handles this QR code to establish a secure connection with the wallet application.

Exchange presentation request and response

1. Once the verifier has scanned the QR code presented by the wallet application, your application must retrieve the information from that QR code and use it to establish a secure connection between the verifier and holder devices.
2. The verifier then uses this secure connection to send a presentation request to which the holder wallet application responds with a presentation response.
3. Finally, the SDK verifies any mDocs included in the response and stores the verification results in a variable.

To achieve this, your application must use the SDK’s createProximityPresentationSession  function that takes a string retrieved from the QR code and uses it to establish a proximity presentation session with the wallet application and initiate the presentation workflow.

This function takes a listener argument of type ProximityPresentationSessionListener delegate, which will receive proximity presentation session events.

1. Add the following code under the Verify mDocs - Step 3.1: Extend VerifierViewModel class to extend the VerifierViewModel class with the ProximityPresentationSessionListener protocol:

   Swift

   extension VerifierViewModel: ProximityPresentationSessionListener {
    
               public func onEstablished() {
                   sendDeviceRequest()
               }
    
               public func onTerminated(error: (any Error)?) {
                   print("Session Terminated")
               }
           }

   Now, as soon as a connection is established, the app will send a device request. You will implement the functionality of sendDeviceRequest() in VerifierViewModel later in the tutorial.

2. Replace the print statement under the // Verify mDocs - Step 3.2: Create setupProximityPresentationSession comment with the following code to call the SDK’s createProximityPresentationSession function, passing a device engagement string (retrieved from a QR code) and self as a listener to create a proximity presentation session:

   Swift

    mobileCredentialVerifier.createProximityPresentationSession(encodedDeviceEngagementString: deviceEngagementString, listener: self)

3. Replace the print statement under the // Verify mDocs - Step 3.3: Create sendDeviceRequest function comment with following code to implement the logic to send a device request:

   Swift

       Task { @MainActor in
           receivedDocuments = []
           do {
               // Navigate to response screen
               navigationPath.append(NavigationState.viewResponse)
               // Request mDocs
               let deviceResponse = try await mobileCredentialVerifier.sendProximityPresentationRequest(
                   request: [mobileCredentialRequest]
               )
    
               // Assign new values from the response
               receivedDocuments = deviceResponse.credentials ?? []
               // Terminate session after response is received (optional)
               await mobileCredentialVerifier.terminateProximityPresentationSession()
           } catch {
               print(error)
               receivedDocuments = []
           }
       }

   This function now implements the following logic:

   1. Navigate to the viewResponse screen.
   2. Send a proximity presentation request using the SDK’s requestMobileCredentials function.
   3. Store the wallet response in the deviceResponse variable. This includes the verification results of any credentials included in the response.
   4. Store the verification results in the receivedDocuments variable.
   5. Terminate the presentation session once the response is received.

Display verification results

You will now create a new view that is automatically displayed when verification results are available.

1. Create a new file named DocumentView and add the following code to display available verification results:

   Swift

   import MobileCredentialVerifierSDK
   import SwiftUI
    
       struct DocumentView: View {
    
           var viewModel: DocumentViewModel
    
           var body: some View {
               VStack(alignment: .leading, spacing: 10) {
                   Text(viewModel.docType)
                       .font(.title)
                       .fontWeight(.bold)
                       .padding(.bottom, 5)
    
                   Text(viewModel.verificationResult)
                       .font(.title)
                       .fontWeight(.bold)
                       .foregroundStyle(viewModel.verificationFailedReason == nil ? .green : .red)
                       .padding(.bottom, 5)
    
                   if let verificationFailedReason = viewModel.verificationFailedReason {
                       Text(verificationFailedReason)
                           .font(.title3)
                           .fontWeight(.bold)
                           .foregroundStyle(.red)
                           .padding(.bottom, 5)
                   }
    
                   ForEach(viewModel.namespacesAndClaims.keys.sorted(), id: \.self) { key in
                       VStack(alignment: .leading, spacing: 5) {
                           Text(key)
                               .font(.headline)
                               .padding(.vertical, 5)
                               .padding(.horizontal, 10)
                               .background(Color.gray.opacity(0.2))
                               .cornerRadius(5)
    
                           ForEach(viewModel.namespacesAndClaims[key]!.keys.sorted(), id: \.self) { claim in
                               HStack {
                                   Text(claim)
                                       .fontWeight(.semibold)
                                   Spacer()
                                   Text(viewModel.namespacesAndClaims[key]![claim]! ?? "")
                                       .fontWeight(.regular)
                               }
                               .padding(.vertical, 5)
                               .padding(.horizontal, 10)
                               .background(Color.white)
                               .cornerRadius(5)
                               .shadow(radius: 1)
                           }
                       }
                       .padding(.vertical, 5)
                   }
    
                   if !viewModel.claimErrors.isEmpty {
                   Text("Failed Claims:")
                       .font(.headline)
                       .padding(.vertical, 5)
    
                       ForEach(viewModel.claimErrors.keys.sorted(), id: \.self) { key in
                           VStack(alignment: .leading, spacing: 5) {
                               Text(key)
                                   .font(.headline)
                                   .padding(.vertical, 5)
                                   .padding(.horizontal, 10)
                                   .background(Color.gray.opacity(0.2))
                                   .cornerRadius(5)
    
                               ForEach(viewModel.claimErrors[key]!.keys.sorted(), id: \.self) { claim in
                                   HStack {
                                       Text(claim)
                                           .fontWeight(.semibold)
                                       Spacer()
                                       Text(viewModel.claimErrors[key]![claim]! ?? "")
                                           .fontWeight(.regular)
                                   }
                                   .padding(.vertical, 5)
                                   .padding(.horizontal, 10)
                                   .background(Color.white)
                                   .cornerRadius(5)
                                   .shadow(radius: 1)
                               }
                           }
                           .padding(.vertical, 5)
                       }
                   }
               }
               .padding()
               .background(RoundedRectangle(cornerRadius: 10).fill(Color.white).shadow(radius: 5))
               .padding(.horizontal)
           }
       }
    
       // MARK: DocumentViewModel
    
       class DocumentViewModel: ObservableObject {
           let docType: String
           let namespacesAndClaims: [String: [String: String?]]
           let claimErrors: [String: [String: String?]]
           let verificationResult: String
           let verificationFailedReason: String?
    
           init(from presentation: MobileCredentialPresentation) {
               self.docType = presentation.docType
               self.verificationResult = presentation.verificationResult.verified ? "Verified" : "Invalid"
               self.verificationFailedReason = presentation.verificationResult.reason?.message
    
               self.namespacesAndClaims = presentation.claims?.reduce(into: [String: [String: String]]()) { result, outerElement in
                   let (outerKey, innerDict) = outerElement
                   result[outerKey] = innerDict.mapValues { $0.textRepresentation }
               } ?? [:]
    
               self.claimErrors = presentation.claimErrors?.reduce(into: [String: [String: String]]()) { result, outerElement in
                   let (outerKey, innerDict) = outerElement
                   result[outerKey] = innerDict.mapValues { "\($0)" }
               } ?? [:]
           }
       }
    
       // MARK: Helper
       extension MobileCredentialElementValue {
           var textRepresentation: String {
               switch self {
               case .bool(let bool):
                   return "\(bool)"
               case .string(let string):
                   return string
               case .int(let int):
                   return "\(int)"
               case .unsigned(let uInt):
                   return "\(uInt)"
               case .float(let float):
                   return "\(float)"
               case .double(let double):
                   return "\(double)"
               case let .date(date):
                   let dateFormatter = DateFormatter()
                   dateFormatter.dateStyle = .short
                   dateFormatter.timeStyle = .none
                   return dateFormatter.string(from: date)
               case let .dateTime(date):
                   let dateFormatter = DateFormatter()
                   dateFormatter.dateStyle = .short
                   dateFormatter.timeStyle = .short
                   return dateFormatter.string(from: date)
               case .data(let data):
                   return "Data \(data.count) bytes"
               case .map(let dictionary):
                   let result = dictionary.mapValues { value in
                       value.textRepresentation
                   }
                   return "\(result)"
               case .array(let array):
                   return array.reduce("") { partialResult, element in
                       partialResult + element.textRepresentation
                   }
                   .appending("")
               @unknown default:
                   return "Unknown type"
               }
           }
       }

   The DocumentView file comprises the following elements:

   • DocumentView : Basic UI layout for viewing received documents and verification results.
   • DocumentViewModel : This class takes MobileCredentialPresentation and converts its elements into strings to display in the DocumentView.
   • Extension of MobileCredentialElementValue which converts the values of received claims into a human-readable format.

2. Return to the ContentView file and replace the EmptyView() under the // Verify mDocs - Step 4.2: Create PresentationResponseView comment with the following code to display the DocumentView view when verification results are available:

   ContentView

           ZStack {
           if viewModel.receivedDocuments.isEmpty {
               VStack(spacing: 40) {
                   Text("Waiting for response...")
                       .font(.title)
                   ProgressView()
                       .progressViewStyle(.circular)
                       .scaleEffect(2)
               }
           } else {
               ScrollView {
                   ForEach(viewModel.receivedDocuments, id: \.docType) { doc in
                       DocumentView(viewModel: DocumentViewModel(from: doc))
                           .padding(10)
                   }
               }
           }
       }