[Example] Update the app to allow scanning multiple documents

romanmazeev · Feb 2, 2025 · 4de797a · 4de797a
1 parent 8eb7e9b
commit 4de797a
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Showing 3 changed files with 24 additions and 23 deletions.
diff --git a/Example/MRZScannerExample/Camera.swift b/Example/MRZScannerExample/Camera.swift
@@ -6,15 +6,20 @@
 //
 
 @preconcurrency import AVFoundation
-import CoreImage
+@preconcurrency import CoreImage
+import ConcurrencyExtras
 
-actor Camera {
-    nonisolated let captureSession = AVCaptureSession()
+final class Camera: Sendable {
+    let captureSession = AVCaptureSession()
     private let outputSampleBufferDelegate = OutputSampleBufferDelegate()
 
-    var imageStream: AsyncStream<CIImage>? {
+    var imageStream: AsyncStream<CIImage> {
         .init { continuation in
-            outputSampleBufferDelegate.continuation = continuation
+            outputSampleBufferDelegate.continuation.withValue { $0 = continuation }
+
+            continuation.onTermination = { _ in
+                self.outputSampleBufferDelegate.continuation.withValue { $0 = nil }
+            }
         }
     }
 
@@ -68,12 +73,12 @@ actor Camera {
     }
 }
 
-final private class OutputSampleBufferDelegate: NSObject, AVCaptureVideoDataOutputSampleBufferDelegate {
-    var continuation: AsyncStream<CIImage>.Continuation?
+private final class OutputSampleBufferDelegate: NSObject, Sendable, AVCaptureVideoDataOutputSampleBufferDelegate {
+    let continuation: LockIsolated<AsyncStream<CIImage>.Continuation?> = .init(nil)
 
     func captureOutput(_ output: AVCaptureOutput, didOutput sampleBuffer: CMSampleBuffer, from connection: AVCaptureConnection) {
         guard let pixelBuffer = sampleBuffer.imageBuffer else { return }
 
-        continuation?.yield(CIImage(cvPixelBuffer: pixelBuffer))
+        continuation.value?.yield(CIImage(cvPixelBuffer: pixelBuffer))
     }
 }
diff --git a/Example/MRZScannerExample/ContentView.swift b/Example/MRZScannerExample/ContentView.swift
@@ -64,7 +64,14 @@ struct ContentView: View {
         .alert(isPresented: .init(get: { viewModel.result != nil }, set: { _ in viewModel.result = nil })) {
             Alert(
                 title: Text(createAlertTitle(result: viewModel.result!)),
-                message: Text(createAlertMessage(result: viewModel.result!))
+                message: Text(createAlertMessage(result: viewModel.result!)),
+                dismissButton: .default(Text("Restart scanning")) {
+                    Task {
+                        guard let cameraRect, let mrzRect else { return }
+
+                        await viewModel.startMRZScanning(cameraRect: cameraRect, mrzRect: mrzRect)
+                    }
+                }
             )
         }
         .task {
@@ -118,15 +125,6 @@ struct ContentView: View {
     }
 }
 
-extension CGRect: @retroactive Hashable {
-    public func hash(into hasher: inout Hasher) {
-        hasher.combine(origin.x)
-        hasher.combine(origin.y)
-        hasher.combine(size.width)
-        hasher.combine(size.height)
-    }
-}
-
 struct ContentView_Previews: PreviewProvider {
     static var previews: some View {
         ContentView()

diff --git a/Example/MRZScannerExample/ViewModel.swift b/Example/MRZScannerExample/ViewModel.swift
@@ -5,8 +5,8 @@
 //  Created by Roman Mazeev on 01/01/2023.
 //
 
-@preconcurrency import AVFoundation
-@preconcurrency import SwiftUI
+import AVFoundation
+import CoreImage
 import MRZScanner
 import Vision
 
@@ -29,10 +29,8 @@ final class ViewModel: ObservableObject {
     }
 
     func startMRZScanning(cameraRect: CGRect, mrzRect: CGRect) async {
-        guard let imageStream = await camera.imageStream else { return }
-
         do {
-            try await scanImageStream(imageStream, cameraRect: cameraRect, mrzRect: mrzRect)
+            try await scanImageStream(camera.imageStream, cameraRect: cameraRect, mrzRect: mrzRect)
         } catch {
             result = .failure(error)
         }