Introduce BiometricsAuthenticationPresenter

Riot/Modules/SetPinCode/SetupBiometrics/BiometricsAuthenticationPresenter.swift

@@ -0,0 +1,66 @@
+// 
+// Copyright 2020 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import Foundation
+import LocalAuthentication
+
+enum BiometricsAuthenticationPresenterError: Error {
+    case unknown
+}
+
+/// Presenter for user authentication with biometry.
+final class BiometricsAuthenticationPresenter {
+
+    /// Whether the presenter currently showing the biometrics setup or unlock dialog.
+    /// Showing biometrics dialog will cause the app to resign active.
+    /// This property can be used in order to distinguish real resignations and biometrics case.
+    static private(set) var isPresentingBiometricsAuth: Bool = false
+    
+    /// Presents the user authentication with biometry.
+    /// - Parameters:
+    ///   - message: The app-provided reason for requesting authentication, which displays in the authentication dialog presented to the user.
+    ///   - completion: A closure that is executed when policy evaluation finishes. Will be called in main thread.
+    func present(with message: String, completion: @escaping (Result<Void, Error>) -> Void) {
+        //  do not present if already presented
+        guard !BiometricsAuthenticationPresenter.isPresentingBiometricsAuth else {
+            return
+        }
+        BiometricsAuthenticationPresenter.isPresentingBiometricsAuth = true
+
+        LAContext().evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: message) { (success, error) in
+            if success {
+                // Complete after a little delay
+                DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
+                    BiometricsAuthenticationPresenter.isPresentingBiometricsAuth = false
+                    completion(.success(Void()))
+                }
+            } else {
+                let finalError: Error
+                
+                if let error = error {
+                    finalError = error
+                } else {
+                    finalError = BiometricsAuthenticationPresenterError.unknown
+                }
+                
+                DispatchQueue.main.async {
+                    BiometricsAuthenticationPresenter.isPresentingBiometricsAuth = false
+                    completion(.failure(finalError))
+                }
+            }
+        }
+    }
+}

Riot/Modules/SetPinCode/SetupBiometrics/SetupBiometricsViewModel.swift

@@ -29,6 +29,7 @@ final class SetupBiometricsViewModel: SetupBiometricsViewModelType {
     private let viewMode: SetPinCoordinatorViewMode
     private let pinCodePreferences: PinCodePreferences
     private let localAuthenticationService: LocalAuthenticationService
+    private let biometricsAuthenticationPresenter: BiometricsAuthenticationPresenter
     
     // MARK: Public
 
@@ -42,6 +43,7 @@ final class SetupBiometricsViewModel: SetupBiometricsViewModelType {
         self.viewMode = viewMode
         self.pinCodePreferences = pinCodePreferences
         self.localAuthenticationService = LocalAuthenticationService(pinCodePreferences: pinCodePreferences)
+        self.biometricsAuthenticationPresenter = BiometricsAuthenticationPresenter()
     }
     
     deinit {
@@ -76,34 +78,26 @@ final class SetupBiometricsViewModel: SetupBiometricsViewModelType {
     // MARK: - Private
     
     private func enableDisableBiometrics() {
-        LocalAuthenticationService.isShowingBiometrics = true
-        LAContext().evaluatePolicy(.deviceOwnerAuthentication, localizedReason: VectorL10n.biometricsUsageReason) { (success, error) in
-            if success {
-                //  complete after a little delay
-                DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
-                    self.pinCodePreferences.canUseBiometricsToUnlock = nil
-                    self.pinCodePreferences.resetCounters()
-                    self.coordinatorDelegate?.setupBiometricsViewModelDidComplete(self)
-                    LocalAuthenticationService.isShowingBiometrics = false
-                }
-            } else {
-                LocalAuthenticationService.isShowingBiometrics = false
+        biometricsAuthenticationPresenter.present(with: VectorL10n.biometricsUsageReason) { (response) in
+            switch response {
+            case .success:
+                self.pinCodePreferences.canUseBiometricsToUnlock = nil
+                self.pinCodePreferences.resetCounters()
+                self.coordinatorDelegate?.setupBiometricsViewModelDidComplete(self)
+            case .failure:
+                break
             }
         }
     }
     
     private func unlockWithBiometrics() {
-        LocalAuthenticationService.isShowingBiometrics = true
-        LAContext().evaluatePolicy(.deviceOwnerAuthentication, localizedReason: VectorL10n.biometricsUsageReason) { (success, error) in
-            if success {
-                //  complete after a little delay
-                DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
-                    self.pinCodePreferences.canUseBiometricsToUnlock = nil
-                    self.pinCodePreferences.resetCounters()
-                    self.coordinatorDelegate?.setupBiometricsViewModelDidComplete(self)
-                    LocalAuthenticationService.isShowingBiometrics = false
-                }
-            } else {
+        biometricsAuthenticationPresenter.present(with: VectorL10n.biometricsUsageReason) { (response) in
+            switch response {
+            case .success:
+                self.pinCodePreferences.canUseBiometricsToUnlock = nil
+                self.pinCodePreferences.resetCounters()
+                self.coordinatorDelegate?.setupBiometricsViewModelDidComplete(self)
+            case .failure(let error):
                 guard let error = error as NSError? else {
                     return
                 }
@@ -111,13 +105,9 @@ final class SetupBiometricsViewModel: SetupBiometricsViewModelType {
                 if self.localAuthenticationService.shouldLogOutUser() {
                     //  biometrics can't be used until further unlock with pin or a new log in
                     self.pinCodePreferences.canUseBiometricsToUnlock = false
-                    DispatchQueue.main.async {
-                        self.coordinatorDelegate?.setupBiometricsViewModelDidCompleteWithReset(self, dueToTooManyErrors: true)
-                        LocalAuthenticationService.isShowingBiometrics = false
-                    }
+                    self.coordinatorDelegate?.setupBiometricsViewModelDidCompleteWithReset(self, dueToTooManyErrors: true)
                 } else if error.code == LAError.Code.userCancel.rawValue || error.code == LAError.Code.userFallback.rawValue {
                     self.userCancelledUnlockWithBiometrics()
-                    LocalAuthenticationService.isShowingBiometrics = false
                 }
             }
         }