[PM-39361] fix: Restart card scanner after camera interruption or reopen

BitwardenShared/UI/Vault/VaultItem/AddEditItem/AddEditCardItem/CardScannerView.swift

@@ -1,5 +1,6 @@
 import BitwardenResources
 import SwiftUI
+import UIKit
 import VisionKit
 
 // MARK: - CardScannerWrapperView
@@ -21,6 +22,12 @@ struct CardScannerWrapperView: View {
     /// Drives `startScanning()`/`stopScanning()` via the SwiftUI view lifecycle.
     @SwiftUI.State private var isScanning = false
 
+    /// Counts how many stop-then-restart cycles have been attempted this session in response to
+    /// genuine scanner failures (`onScannerUnavailable`). Capped at 2 to avoid infinite loops;
+    /// resets on each `.onAppear`. Foreground-triggered restarts do not count against this budget.
+    @SwiftUI.State private var scannerRetryCount = 0
+
+    /// Dismisses the sheet when the scanner gives up after exhausting retries.
     @Environment(\.dismiss) private var dismiss
 
     var body: some View {
@@ -35,11 +42,15 @@ struct CardScannerWrapperView: View {
                     scanner: scanner,
                     onLinesUpdated: onLinesUpdated,
                     isScanning: $isScanning,
+                    onScannerUnavailable: restartScanning,
                 )
                 .padding(.horizontal, 12)
                 .padding(.top, 12)
                 .padding(.bottom, 35)
-                .onAppear { isScanning = true }
+                .onAppear {
+                    scannerRetryCount = 0
+                    isScanning = true
+                }
                 .onDisappear { isScanning = false }
             }
             .navigationTitle(Localizations.scanCard)
@@ -51,6 +62,43 @@ struct CardScannerWrapperView: View {
             }
         }
         .navigationViewStyle(.stack)
+        .onReceive(NotificationCenter.default.publisher(for: UIApplication.willEnterForegroundNotification)) { _ in
+            // `scenePhase` is driven by SwiftUI's own `Scene`/`App` lifecycle and is unreliable
+            // for views hosted in a UIKit app via `UIHostingController`, so foreground transitions
+            // are observed directly via `UIApplication` notifications instead.
+            if isScanning {
+                resumeScanningAfterForeground()
+            }
+        }
+    }
+
+    // MARK: Private
+
+    /// Stops scanning, waits 300 ms for the camera to fully release, then restarts.
+    /// After two retries the sheet is dismissed so the user is never left with a blank screen.
+    private func restartScanning() {
+        guard scannerRetryCount < 2 else {
+            dismiss()
+            return
+        }
+        scannerRetryCount += 1
+        isScanning = false
+        Task { @MainActor in
+            try? await Task.sleep(for: .milliseconds(300))
+            isScanning = true
+        }
+    }
+
+    /// Stops scanning, waits 300 ms for the camera to fully release, then restarts, in response to
+    /// the app returning to the foreground. Unlike `restartScanning()`, this does not consume the
+    /// failure retry budget, since a foreground transition is a routine occurrence rather than a
+    /// scanner failure and would otherwise exhaust the budget after a couple of normal app switches.
+    private func resumeScanningAfterForeground() {
+        isScanning = false
+        Task { @MainActor in
+            try? await Task.sleep(for: .milliseconds(300))
+            isScanning = true
+        }
     }
 }
 
@@ -75,6 +123,10 @@ struct CardScannerView: UIViewControllerRepresentable {
     /// When `true`, scanning is active; when `false`, scanning is stopped.
     @Binding var isScanning: Bool
 
+    /// Called when `startScanning()` throws or the scanner becomes unavailable at runtime
+    /// (e.g. camera interrupted). The wrapper uses this to schedule a stop-then-restart cycle.
+    var onScannerUnavailable: (() -> Void)?
+
     // MARK: Static methods for UIViewControllerRepresentable
 
     /// Stops scanning and clears the delegate when SwiftUI removes this representable from the hierarchy,
@@ -103,7 +155,7 @@ struct CardScannerView: UIViewControllerRepresentable {
     // MARK: UIViewControllerRepresentable
 
     func makeCoordinator() -> Coordinator {
-        Coordinator(onLinesUpdated: onLinesUpdated)
+        Coordinator(onLinesUpdated: onLinesUpdated, onScannerUnavailable: onScannerUnavailable)
     }
 
     func makeUIViewController(context: Context) -> DataScannerViewController {
@@ -114,7 +166,11 @@ struct CardScannerView: UIViewControllerRepresentable {
 
     func updateUIViewController(_ uiViewController: DataScannerViewController, context: Context) {
         if isScanning {
-            try? uiViewController.startScanning()
+            do {
+                try uiViewController.startScanning()
+            } catch {
+                DispatchQueue.main.async { context.coordinator.onScannerUnavailable?() }
+            }
         } else {
             uiViewController.stopScanning()
         }
@@ -139,10 +195,15 @@ extension CardScannerView {
 
         let onLinesUpdated: ([String]) -> Void
 
+        /// Forwarded from `CardScannerView.onScannerUnavailable`; called when `startScanning()`
+        /// fails or the camera is interrupted at runtime.
+        var onScannerUnavailable: (() -> Void)?
+
         // MARK: Initialization
 
-        init(onLinesUpdated: @escaping ([String]) -> Void) {
+        init(onLinesUpdated: @escaping ([String]) -> Void, onScannerUnavailable: (() -> Void)?) {
             self.onLinesUpdated = onLinesUpdated
+            self.onScannerUnavailable = onScannerUnavailable
         }
 
         // MARK: DataScannerViewControllerDelegate
@@ -173,6 +234,13 @@ extension CardScannerView {
             updateLines(from: allItems)
         }
 
+        func dataScanner(
+            _ dataScanner: DataScannerViewController,
+            becameUnavailableWithError error: DataScannerViewController.ScanningUnavailable,
+        ) {
+            onScannerUnavailable?()
+        }
+
         // MARK: Private Helpers
 
         private func updateLines(from items: [RecognizedItem]) {

BitwardenShared/UI/Vault/VaultItem/AddEditItem/AddEditCardItem/CardScannerViewTests.swift

@@ -0,0 +1,57 @@
+import VisionKit
+import XCTest
+
+@testable import BitwardenShared
+
+// MARK: - CardScannerViewTests
+
+/// Tests for `CardScannerView.Coordinator`.
+///
+/// `CardScannerWrapperView`'s retry/foreground-resume logic is driven by SwiftUI `@State` and cannot
+/// be meaningfully exercised without a live view host, so it is not covered here.
+///
+@available(iOS 16.0, *)
+class CardScannerViewTests: BitwardenTestCase {
+    // MARK: Tests
+
+    /// `dataScanner(_:becameUnavailableWithError:)` calls `onScannerUnavailable` when the scanner
+    /// reports an `unsupported` error.
+    @MainActor
+    func test_becameUnavailableWithError_callsOnScannerUnavailable_unsupported() {
+        var callbackInvoked = false
+        let subject = CardScannerView.Coordinator(
+            onLinesUpdated: { _ in },
+            onScannerUnavailable: { callbackInvoked = true },
+        )
+
+        subject.dataScanner(CardScannerView.makeScanner(), becameUnavailableWithError: .unsupported)
+
+        XCTAssertTrue(callbackInvoked)
+    }
+
+    /// `dataScanner(_:becameUnavailableWithError:)` calls `onScannerUnavailable` when the scanner
+    /// reports a `cameraRestricted` error.
+    @MainActor
+    func test_becameUnavailableWithError_callsOnScannerUnavailable_cameraRestricted() {
+        var callbackInvoked = false
+        let subject = CardScannerView.Coordinator(
+            onLinesUpdated: { _ in },
+            onScannerUnavailable: { callbackInvoked = true },
+        )
+
+        subject.dataScanner(CardScannerView.makeScanner(), becameUnavailableWithError: .cameraRestricted)
+
+        XCTAssertTrue(callbackInvoked)
+    }
+
+    /// `dataScanner(_:becameUnavailableWithError:)` does not crash when `onScannerUnavailable` is nil.
+    @MainActor
+    func test_becameUnavailableWithError_nilCallback_doesNotCrash() {
+        let subject = CardScannerView.Coordinator(
+            onLinesUpdated: { _ in },
+            onScannerUnavailable: nil,
+        )
+
+        subject.dataScanner(CardScannerView.makeScanner(), becameUnavailableWithError: .unsupported)
+    }
+}