Debounce PIN entry to show the last digit before submitting. (#2017)

ElementX/Sources/Screens/AppLock/AppLockScreen/AppLockScreenModels.swift

@@ -60,8 +60,6 @@ enum AppLockScreenAlertType {
 }
 
 enum AppLockScreenViewAction {
-    /// Attempt to unlock the app with the supplied PIN code.
-    case submitPINCode
     /// Clears the PIN code after a failure animation.
     case clearPINCode
     /// The user didn't heed the warnings and can't remember their PIN.

ElementX/Sources/Screens/AppLock/AppLockScreen/AppLockScreenViewModel.swift

@@ -36,6 +36,16 @@ class AppLockScreenViewModel: AppLockScreenViewModelType, AppLockScreenViewModel
             .weakAssign(to: \.state.numberOfPINAttempts, on: self)
             .store(in: &cancellables)
         
+        context.$viewState
+            .map(\.bindings.pinCode)
+            .removeDuplicates()
+            .debounce(for: 0.05, scheduler: DispatchQueue.main) // Allow the last digit to be briefly shown
+            .sink { [weak self] pinCode in
+                guard pinCode.count == 4 else { return }
+                self?.submit(pinCode)
+            }
+            .store(in: &cancellables)
+        
         showForceLogoutAlertIfNeeded()
     }
     
@@ -45,8 +55,6 @@ class AppLockScreenViewModel: AppLockScreenViewModelType, AppLockScreenViewModel
         MXLog.info("View model: received view action: \(viewAction)")
         
         switch viewAction {
-        case .submitPINCode:
-            submitPINCode()
         case .clearPINCode:
             state.bindings.pinCode = ""
         case .forgotPIN:
@@ -56,8 +64,8 @@ class AppLockScreenViewModel: AppLockScreenViewModelType, AppLockScreenViewModel
     
     // MARK: - Private
     
-    private func submitPINCode() {
-        guard appLockService.unlock(with: state.bindings.pinCode) else {
+    private func submit(_ pinCode: String) {
+        guard appLockService.unlock(with: pinCode) else {
             handleInvalidPIN()
             return
         }

ElementX/Sources/Screens/AppLock/AppLockScreen/View/AppLockScreen.swift

@@ -49,10 +49,6 @@ struct AppLockScreen: View {
                     .accessibilityValue(L10n.a11yDigitsEntered(context.viewState.numberOfDigitsEntered))
                 
                 AppLockScreenPINKeypad(pinCode: $context.pinCode)
-                    .onChange(of: context.pinCode) { newValue in
-                        guard newValue.count == 4 else { return }
-                        context.send(viewAction: .submitPINCode)
-                    }
             }
         } bottomContent: {
             Button(L10n.screenAppLockForgotPin) {

ElementX/Sources/Screens/AppLock/AppLockSetupPINScreen/AppLockSetupPINScreenModels.swift

@@ -88,8 +88,6 @@ enum AppLockSetupPINScreenAlertType {
 }
 
 enum AppLockSetupPINScreenViewAction {
-    /// Confirm the entered PIN.
-    case submitPINCode
     /// Stop entering a PIN.
     case cancel
 }

ElementX/Sources/Screens/AppLock/AppLockSetupPINScreen/AppLockSetupPINScreenViewModel.swift

@@ -38,6 +38,16 @@ class AppLockSetupPINScreenViewModel: AppLockSetupPINScreenViewModelType, AppLoc
         appLockService.numberOfPINAttempts
             .weakAssign(to: \.state.numberOfUnlockAttempts, on: self)
             .store(in: &cancellables)
+        
+        context.$viewState
+            .map(\.bindings.pinCode)
+            .removeDuplicates()
+            .debounce(for: 0.1, scheduler: DispatchQueue.main) // Show the last digit for long enough to be read.
+            .sink { [weak self] pinCode in
+                guard pinCode.count == 4 else { return }
+                self?.submit(pinCode)
+            }
+            .store(in: &cancellables)
     }
     
     // MARK: - Public
@@ -46,8 +56,6 @@ class AppLockSetupPINScreenViewModel: AppLockSetupPINScreenViewModelType, AppLoc
         MXLog.info("View model: received view action: \(viewAction)")
         
         switch viewAction {
-        case .submitPINCode:
-            submitPINCode()
         case .cancel:
             actionsSubject.send(.cancel)
         }
@@ -56,7 +64,7 @@ class AppLockSetupPINScreenViewModel: AppLockSetupPINScreenViewModelType, AppLoc
     // MARK: - Private
     
     /// Handle the entered PIN code.
-    private func submitPINCode() {
+    private func submit(_ pinCode: String) {
         switch state.mode {
         case .create:
             createPIN()

ElementX/Sources/Screens/AppLock/AppLockSetupPINScreen/View/AppLockSetupPINScreen.swift

@@ -43,10 +43,6 @@ struct AppLockSetupPINScreen: View {
                 PINTextField(pinCode: $context.pinCode,
                              isSecure: context.viewState.mode == .unlock)
                     .focused($textFieldFocus)
-                    .onChange(of: context.pinCode) { newValue in
-                        guard newValue.count == 4 else { return }
-                        context.send(viewAction: .submitPINCode)
-                    }
             }
             .padding(.horizontal, 16)
             .padding(.top, UIConstants.iconTopPaddingToNavigationBar)