Add UI changes for selecting back camera in HostApp

Author: thisisabhash

HostApp/HostApp/Views/ExampleLivenessView.swift

@@ -9,24 +9,28 @@ import SwiftUI
 import FaceLiveness
 
 struct ExampleLivenessView: View {
-    @Binding var isPresented: Bool
+    @Binding var containerViewState: ContainerViewState
     @ObservedObject var viewModel: ExampleLivenessViewModel
 
-    init(sessionID: String, isPresented: Binding<Bool>) {
-        self.viewModel = .init(sessionID: sessionID)
-        self._isPresented = isPresented
+    init(sessionID: String, containerViewState: Binding<ContainerViewState>) {
+        self._containerViewState = containerViewState
+        if case let .liveness(selectedCamera) = _containerViewState.wrappedValue {
+            self.viewModel = .init(sessionID: sessionID, presentationState: .liveness(selectedCamera))
+        } else {
+            self.viewModel = .init(sessionID: sessionID)
+        }
     }
 
     var body: some View {
         switch viewModel.presentationState {
-        case .liveness:
+        case .liveness(let camera):
             FaceLivenessDetectorView(
                 sessionID: viewModel.sessionID,
                 region: "us-east-1",
-                challengeOptions: .init(faceMovementChallengeOption: FaceMovementChallengeOption(camera: .front),
+                challengeOptions: .init(faceMovementChallengeOption: FaceMovementChallengeOption(camera: camera),
                                         faceMovementAndLightChallengeOption: FaceMovementAndLightChallengeOption()),
                 isPresented:  Binding(
-                    get: { viewModel.presentationState == .liveness },
+                    get: { viewModel.presentationState == .liveness(camera) },
                     set: { _ in }
                 ),
                 onCompletion: { result in
@@ -35,11 +39,11 @@ struct ExampleLivenessView: View {
                         case .success:
                             withAnimation { viewModel.presentationState = .result }
                         case .failure(.sessionNotFound), .failure(.cameraPermissionDenied), .failure(.accessDenied):
-                            viewModel.presentationState = .liveness
-                            isPresented = false
+                            viewModel.presentationState = .liveness(camera)
+                            containerViewState = .startSession
                         case .failure(.userCancelled):
-                            viewModel.presentationState = .liveness
-                            isPresented = false
+                            viewModel.presentationState = .liveness(camera)
+                            containerViewState = .startSession
                         case .failure(.sessionTimedOut):
                             viewModel.presentationState = .error(.sessionTimedOut)
                         case .failure(.socketClosed):
@@ -64,11 +68,11 @@ struct ExampleLivenessView: View {
                     }
                 }
             )
-            .id(isPresented)
+            .id(containerViewState)
         case .result:
             LivenessResultView(
                 sessionID: viewModel.sessionID,
-                onTryAgain: { isPresented = false },
+                onTryAgain: { containerViewState = .startSession },
                 content: {
                     LivenessResultContentView(fetchResults: viewModel.fetchLivenessResult)
                 }
@@ -77,7 +81,7 @@ struct ExampleLivenessView: View {
         case .error(let detectionError):
             LivenessResultView(
                 sessionID: viewModel.sessionID,
-                onTryAgain: { isPresented = false },
+                onTryAgain: { containerViewState = .startSession },
                 content: {
                     switch detectionError {
                     case .socketClosed:

HostApp/HostApp/Views/ExampleLivenessViewModel.swift

@@ -10,11 +10,12 @@ import FaceLiveness
 import Amplify
 
 class ExampleLivenessViewModel: ObservableObject {
-    @Published var presentationState = PresentationState.liveness
+    @Published var presentationState: PresentationState = .liveness(.front)
     let sessionID: String
 
-    init(sessionID: String) {
+    init(sessionID: String, presentationState: PresentationState = .liveness(.front)) {
         self.sessionID = sessionID
+        self.presentationState = presentationState
     }
 
     func fetchLivenessResult() async throws -> LivenessResultContentView.Result {
@@ -30,6 +31,6 @@ class ExampleLivenessViewModel: ObservableObject {
     }
 
     enum PresentationState: Equatable {
-        case liveness, result, error(FaceLivenessDetectionError)
+        case liveness(LivenessCamera), result, error(FaceLivenessDetectionError)
     }
 }

HostApp/HostApp/Views/RootView.swift

@@ -6,25 +6,32 @@
 //
 
 import SwiftUI
+import FaceLiveness
 
 struct RootView: View {
     @EnvironmentObject var sceneDelegate: SceneDelegate
     @State var sessionID = ""
-    @State var isPresentingContainerView = false
+    @State var containerViewState = ContainerViewState.startSession
 
     var body: some View {
-        if isPresentingContainerView {
+        switch containerViewState {
+        case .liveness:
             ExampleLivenessView(
                 sessionID: sessionID,
-                isPresented: $isPresentingContainerView
+                containerViewState: $containerViewState
             )
-        } else {
+        case .startSession:
             StartSessionView(
                 sessionID: $sessionID,
-                isPresentingContainerView: $isPresentingContainerView
+                containerViewState: $containerViewState
             )
             .background(Color.dynamicColors(light: .white, dark: .secondarySystemBackground))
             .edgesIgnoringSafeArea(.all)
         }
     }
 }
+
+enum ContainerViewState: Hashable {
+    case liveness(LivenessCamera)
+    case startSession
+}

HostApp/HostApp/Views/StartSessionView.swift

@@ -12,7 +12,7 @@ struct StartSessionView: View {
     @EnvironmentObject var sceneDelegate: SceneDelegate
     @ObservedObject var viewModel = StartSessionViewModel()
     @Binding var sessionID: String
-    @Binding var isPresentingContainerView: Bool
+    @Binding var containerViewState: ContainerViewState
     @State private var showAlert = false
 
     var body: some View {
@@ -26,7 +26,7 @@ struct StartSessionView: View {
             )
 
             button(
-                text: "Create Liveness Session",
+                text: "Create Liveness Session (front camera)",
                 backgroundColor: .dynamicColors(
                     light: .hex("#047D95"),
                     dark: .hex("#7dd6e8")
@@ -35,7 +35,7 @@ struct StartSessionView: View {
                     viewModel.createSession { sessionId, err in
                         if let sessionId = sessionId {
                             sessionID = sessionId
-                            isPresentingContainerView = true
+                            containerViewState = .liveness(.front)
                         }
 
                         showAlert = err != nil
@@ -50,7 +50,38 @@ struct StartSessionView: View {
                     dismissButton: .default(
                                     Text("OK"),
                                     action: {
-                                        isPresentingContainerView = false
+                                        containerViewState = .startSession
+                                    }
+                    )
+                )
+            }
+            
+            button(
+                text: "Create Liveness Session (back camera)",
+                backgroundColor: .dynamicColors(
+                    light: .hex("#047D95"),
+                    dark: .hex("#7dd6e8")
+                ),
+                action: {
+                    viewModel.createSession { sessionId, err in
+                        if let sessionId = sessionId {
+                            sessionID = sessionId
+                            containerViewState = .liveness(.back)
+                        }
+
+                        showAlert = err != nil
+                    }
+                },
+                enabled: viewModel.isSignedIn
+            )
+            .alert(isPresented: $showAlert) {
+                Alert(
+                    title: Text("Error Creating Liveness Session"),
+                    message: Text("Unable to create a liveness session id.  Please try again."),
+                    dismissButton: .default(
+                                    Text("OK"),
+                                    action: {
+                                        containerViewState = .startSession
                                     }
                     )
                 )