From e911834cc45daf46b760443004598a0f5c8e3917 Mon Sep 17 00:00:00 2001
From: Akshat Gandhi <54901287+AkshatG6@users.noreply.github.com>
Date: Mon, 15 Sep 2025 08:55:36 -0700
Subject: [PATCH 1/8] Updated sample app to support auth_time

---
 .../Shared/DaysUntilBirthday.swift            |  1 +
 .../Services/GoogleSignInAuthenticator.swift  | 36 +++++++++++++++++--
 .../ViewModels/AuthenticationViewModel.swift  |  9 ++++-
 .../iOS/UserProfileView.swift                 |  3 ++
 .../macOS/UserProfileView.swift               |  3 ++
 5 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/Samples/Swift/DaysUntilBirthday/Shared/DaysUntilBirthday.swift b/Samples/Swift/DaysUntilBirthday/Shared/DaysUntilBirthday.swift
index afa3083f..beece9dc 100644
--- a/Samples/Swift/DaysUntilBirthday/Shared/DaysUntilBirthday.swift
+++ b/Samples/Swift/DaysUntilBirthday/Shared/DaysUntilBirthday.swift
@@ -29,6 +29,7 @@ struct DaysUntilBirthday: App {
           GIDSignIn.sharedInstance.restorePreviousSignIn { user, error in
             if let user = user {
               self.authViewModel.state = .signedIn(user)
+              self.authViewModel.authTime = UserDefaults.standard.object(forKey: "authTime") as? Date
             } else if let error = error {
               self.authViewModel.state = .signedOut
               print("There was an error restoring the previous sign-in: \(error)")
diff --git a/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift b/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift
index e12d79a2..5cd982a4 100644
--- a/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift
+++ b/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift
@@ -36,12 +36,14 @@ final class GoogleSignInAuthenticator: ObservableObject {
       return
     }
     let manualNonce = UUID().uuidString
+    let tokenClaims: Set<GIDTokenClaim> = Set([GIDTokenClaim.authTime()])
 
     GIDSignIn.sharedInstance.signIn(
       withPresenting: rootViewController,
       hint: nil,
       additionalScopes: nil,
-      nonce: manualNonce
+      nonce: manualNonce,
+      tokenClaims: tokenClaims
     ) { signInResult, error in
       guard let signInResult = signInResult else {
         print("Error! \(String(describing: error))")
@@ -57,6 +59,10 @@ final class GoogleSignInAuthenticator: ObservableObject {
         assertionFailure("ERROR: Returned nonce doesn't match manual nonce!")
         return
       }
+      if let authTimeDate = self.decodeAuthTime(fromJWT: idToken) {
+        self.authViewModel.authTime = authTimeDate
+        UserDefaults.standard.set(authTimeDate, forKey: "authTime")
+      }
       self.authViewModel.state = .signedIn(signInResult.user)
     }
 
@@ -66,11 +72,27 @@ final class GoogleSignInAuthenticator: ObservableObject {
       return
     }
 
-    GIDSignIn.sharedInstance.signIn(withPresenting: presentingWindow) { signInResult, error in
+    let tokenClaims: Set<GIDTokenClaim> = Set([GIDTokenClaim.authTime()])
+
+    GIDSignIn.sharedInstance.signIn(
+      withPresenting: presentingWindow,
+      tokenClaims: tokenClaims
+      ) { signInResult, error in
       guard let signInResult = signInResult else {
         print("Error! \(String(describing: error))")
         return
       }
+
+      // If the idToken is nil, we cannot get the authTime, so we treat this
+      // as a failure for the app's sign-in flow and return.
+      guard let idToken = signInResult.user.idToken?.tokenString else {
+        print("Error: idToken is missing from signInResult.")
+        return
+      }
+      if let authTimeDate = self.decodeAuthTime(fromJWT: idToken) {
+        self.authViewModel.authTime = authTimeDate
+        UserDefaults.standard.set(authTimeDate, forKey: "authTime")
+      }
       self.authViewModel.state = .signedIn(signInResult.user)
     }
 #endif
@@ -154,6 +176,16 @@ private extension GoogleSignInAuthenticator {
     return nonce
   }
 
+  func decodeAuthTime(fromJWT jwt: String) -> Date? {
+    let segments = jwt.components(separatedBy: ".")
+    guard segments.count > 1,
+          let parts = decodeJWTSegment(segments[1]),
+          let authTimeInterval = parts["auth_time"] as? TimeInterval else {
+      return nil
+    }
+    return Date(timeIntervalSince1970: authTimeInterval)
+  }
+
   func decodeJWTSegment(_ segment: String) -> [String: Any]? {
     guard let segmentData = base64UrlDecode(segment),
           let segmentJSON = try? JSONSerialization.jsonObject(with: segmentData, options: []),
diff --git a/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift b/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
index 15bee104..c667d19c 100644
--- a/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
+++ b/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
@@ -22,6 +22,7 @@ final class AuthenticationViewModel: ObservableObject {
   /// The user's log in status.
   /// - note: This will publish updates when its value changes.
   @Published var state: State
+  @Published var authTime: Date?
   private var authenticator: GoogleSignInAuthenticator {
     return GoogleSignInAuthenticator(authViewModel: self)
   }
@@ -69,7 +70,13 @@ final class AuthenticationViewModel: ObservableObject {
   @MainActor func addBirthdayReadScope(completion: @escaping () -> Void) {
       authenticator.addBirthdayReadScope(completion: completion)
   }
-
+  
+  var formattedAuthTimeString: String? {
+          guard let date = authTime else { return nil }
+          let formatter = DateFormatter()
+          formatter.dateFormat = "dd/MM/yyyy"
+          return formatter.string(from: date)
+  }
 }
 
 extension AuthenticationViewModel {
diff --git a/Samples/Swift/DaysUntilBirthday/iOS/UserProfileView.swift b/Samples/Swift/DaysUntilBirthday/iOS/UserProfileView.swift
index 93366f47..929ec3a2 100644
--- a/Samples/Swift/DaysUntilBirthday/iOS/UserProfileView.swift
+++ b/Samples/Swift/DaysUntilBirthday/iOS/UserProfileView.swift
@@ -35,6 +35,9 @@ struct UserProfileView: View {
               Text(userProfile.name)
                 .font(.headline)
               Text(userProfile.email)
+              if let authTimeString = authViewModel.formattedAuthTimeString {
+                  Text("Last sign-in date: \(authTimeString)")
+              }
             }
           }
           NavigationLink(NSLocalizedString("View Days Until Birthday", comment: "View birthday days"),
diff --git a/Samples/Swift/DaysUntilBirthday/macOS/UserProfileView.swift b/Samples/Swift/DaysUntilBirthday/macOS/UserProfileView.swift
index d7faad97..c19a716f 100644
--- a/Samples/Swift/DaysUntilBirthday/macOS/UserProfileView.swift
+++ b/Samples/Swift/DaysUntilBirthday/macOS/UserProfileView.swift
@@ -19,6 +19,9 @@ struct UserProfileView: View {
               Text(userProfile.name)
                 .font(.headline)
               Text(userProfile.email)
+              if let authTimeString = authViewModel.formattedAuthTimeString {
+                  Text("Last sign-in date: \(authTimeString)")
+              }
             }
           }
           Button(NSLocalizedString("Sign Out", comment: "Sign out button"), action: signOut)

From d42c329f3b0587cc2479500ac5462217bb08cf1e Mon Sep 17 00:00:00 2001
From: Akshat Gandhi <54901287+AkshatG6@users.noreply.github.com>
Date: Mon, 15 Sep 2025 09:11:02 -0700
Subject: [PATCH 2/8] Updated date format for showing last authentication time
 from  to

---
 .../Shared/ViewModels/AuthenticationViewModel.swift             | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift b/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
index c667d19c..d0f28cb4 100644
--- a/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
+++ b/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
@@ -74,7 +74,7 @@ final class AuthenticationViewModel: ObservableObject {
   var formattedAuthTimeString: String? {
           guard let date = authTime else { return nil }
           let formatter = DateFormatter()
-          formatter.dateFormat = "dd/MM/yyyy"
+          formatter.dateFormat = "MM/dd/yyyy"
           return formatter.string(from: date)
   }
 }

From cfae9ba8d338d2966c8640665020ccef08fbebf7 Mon Sep 17 00:00:00 2001
From: Akshat Gandhi <54901287+AkshatG6@users.noreply.github.com>
Date: Mon, 15 Sep 2025 10:26:29 -0700
Subject: [PATCH 3/8] Updated GoogleSignInAuthenticator to reduce code
 duplication

---
 .../Shared/Services/GoogleSignInAuthenticator.swift           | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift b/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift
index 5cd982a4..22af30a5 100644
--- a/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift
+++ b/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift
@@ -20,6 +20,7 @@ import GoogleSignIn
 /// An observable class for authenticating via Google.
 final class GoogleSignInAuthenticator: ObservableObject {
   private var authViewModel: AuthenticationViewModel
+  private var tokenClaims: Set<GIDTokenClaim> = Set([GIDTokenClaim.authTime()])
 
   /// Creates an instance of this authenticator.
   /// - parameter authViewModel: The view model this authenticator will set logged in status on.
@@ -36,7 +37,6 @@ final class GoogleSignInAuthenticator: ObservableObject {
       return
     }
     let manualNonce = UUID().uuidString
-    let tokenClaims: Set<GIDTokenClaim> = Set([GIDTokenClaim.authTime()])
 
     GIDSignIn.sharedInstance.signIn(
       withPresenting: rootViewController,
@@ -72,8 +72,6 @@ final class GoogleSignInAuthenticator: ObservableObject {
       return
     }
 
-    let tokenClaims: Set<GIDTokenClaim> = Set([GIDTokenClaim.authTime()])
-
     GIDSignIn.sharedInstance.signIn(
       withPresenting: presentingWindow,
       tokenClaims: tokenClaims

From 7bdb3e8394dac4f2c2d67d4a464b980b1b522c7d Mon Sep 17 00:00:00 2001
From: Akshat Gandhi <54901287+AkshatG6@users.noreply.github.com>
Date: Mon, 15 Sep 2025 13:23:50 -0700
Subject: [PATCH 4/8] Removed the logic for saving auth_time within User
 Defaults. Added the logic for decoding id token within
 AuthenticationViewModel

---
 .../Shared/DaysUntilBirthday.swift            |  1 -
 .../Services/GoogleSignInAuthenticator.swift  | 27 +---------
 .../ViewModels/AuthenticationViewModel.swift  | 49 ++++++++++++++++++-
 3 files changed, 49 insertions(+), 28 deletions(-)

diff --git a/Samples/Swift/DaysUntilBirthday/Shared/DaysUntilBirthday.swift b/Samples/Swift/DaysUntilBirthday/Shared/DaysUntilBirthday.swift
index beece9dc..afa3083f 100644
--- a/Samples/Swift/DaysUntilBirthday/Shared/DaysUntilBirthday.swift
+++ b/Samples/Swift/DaysUntilBirthday/Shared/DaysUntilBirthday.swift
@@ -29,7 +29,6 @@ struct DaysUntilBirthday: App {
           GIDSignIn.sharedInstance.restorePreviousSignIn { user, error in
             if let user = user {
               self.authViewModel.state = .signedIn(user)
-              self.authViewModel.authTime = UserDefaults.standard.object(forKey: "authTime") as? Date
             } else if let error = error {
               self.authViewModel.state = .signedOut
               print("There was an error restoring the previous sign-in: \(error)")
diff --git a/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift b/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift
index 22af30a5..a2f39a41 100644
--- a/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift
+++ b/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift
@@ -59,10 +59,6 @@ final class GoogleSignInAuthenticator: ObservableObject {
         assertionFailure("ERROR: Returned nonce doesn't match manual nonce!")
         return
       }
-      if let authTimeDate = self.decodeAuthTime(fromJWT: idToken) {
-        self.authViewModel.authTime = authTimeDate
-        UserDefaults.standard.set(authTimeDate, forKey: "authTime")
-      }
       self.authViewModel.state = .signedIn(signInResult.user)
     }
 
@@ -80,17 +76,6 @@ final class GoogleSignInAuthenticator: ObservableObject {
         print("Error! \(String(describing: error))")
         return
       }
-
-      // If the idToken is nil, we cannot get the authTime, so we treat this
-      // as a failure for the app's sign-in flow and return.
-      guard let idToken = signInResult.user.idToken?.tokenString else {
-        print("Error: idToken is missing from signInResult.")
-        return
-      }
-      if let authTimeDate = self.decodeAuthTime(fromJWT: idToken) {
-        self.authViewModel.authTime = authTimeDate
-        UserDefaults.standard.set(authTimeDate, forKey: "authTime")
-      }
       self.authViewModel.state = .signedIn(signInResult.user)
     }
 #endif
@@ -164,7 +149,7 @@ final class GoogleSignInAuthenticator: ObservableObject {
 
 // MARK: Parse nonce from JWT ID Token
 
-private extension GoogleSignInAuthenticator {
+extension GoogleSignInAuthenticator {
   func decodeNonce(fromJWT jwt: String) -> String? {
     let segments = jwt.components(separatedBy: ".")
     guard let parts = decodeJWTSegment(segments[1]),
@@ -174,16 +159,6 @@ private extension GoogleSignInAuthenticator {
     return nonce
   }
 
-  func decodeAuthTime(fromJWT jwt: String) -> Date? {
-    let segments = jwt.components(separatedBy: ".")
-    guard segments.count > 1,
-          let parts = decodeJWTSegment(segments[1]),
-          let authTimeInterval = parts["auth_time"] as? TimeInterval else {
-      return nil
-    }
-    return Date(timeIntervalSince1970: authTimeInterval)
-  }
-
   func decodeJWTSegment(_ segment: String) -> [String: Any]? {
     guard let segmentData = base64UrlDecode(segment),
           let segmentJSON = try? JSONSerialization.jsonObject(with: segmentData, options: []),
diff --git a/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift b/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
index d0f28cb4..fdc65fb5 100644
--- a/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
+++ b/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
@@ -22,10 +22,21 @@ final class AuthenticationViewModel: ObservableObject {
   /// The user's log in status.
   /// - note: This will publish updates when its value changes.
   @Published var state: State
-  @Published var authTime: Date?
   private var authenticator: GoogleSignInAuthenticator {
     return GoogleSignInAuthenticator(authViewModel: self)
   }
+
+  // 3. Change authTime to a computed property
+  var authTime: Date? {
+    switch state {
+    case .signedIn(let user):
+      guard let idToken = user.idToken?.tokenString else { return nil }
+      return decodeAuthTime(fromJWT: idToken)
+    case .signedOut:
+      return nil
+    }
+  }
+
   /// The user-authorized scopes.
   /// - note: If the user is logged out, then this will default to empty.
   var authorizedScopes: [String] {
@@ -79,6 +90,42 @@ final class AuthenticationViewModel: ObservableObject {
   }
 }
 
+private extension AuthenticationViewModel {
+    func decodeAuthTime(fromJWT jwt: String) -> Date? {
+        let segments = jwt.components(separatedBy: ".")
+        guard segments.count > 1,
+              let parts = decodeJWTSegment(segments[1]),
+              let authTimeInterval = parts["auth_time"] as? TimeInterval else {
+            return nil
+        }
+        return Date(timeIntervalSince1970: authTimeInterval)
+    }
+
+    func decodeJWTSegment(_ segment: String) -> [String: Any]? {
+        guard let segmentData = base64UrlDecode(segment),
+              let segmentJSON = try? JSONSerialization.jsonObject(with: segmentData, options: []),
+              let payload = segmentJSON as? [String: Any] else {
+            return nil
+        }
+        return payload
+    }
+
+    func base64UrlDecode(_ value: String) -> Data? {
+        var base64 = value
+            .replacingOccurrences(of: "-", with: "+")
+            .replacingOccurrences(of: "_", with: "/")
+
+        let length = Double(base64.lengthOfBytes(using: String.Encoding.utf8))
+        let requiredLength = 4 * ceil(length / 4.0)
+        let paddingLength = requiredLength - length
+        if paddingLength > 0 {
+            let padding = "".padding(toLength: Int(paddingLength), withPad: "=", startingAt: 0)
+            base64 = base64 + padding
+        }
+        return Data(base64Encoded: base64, options: .ignoreUnknownCharacters)
+    }
+}
+
 extension AuthenticationViewModel {
   /// An enumeration representing logged in status.
   enum State {

From 98b388d0db36f556f51cd9cdde52198c75cf3a8b Mon Sep 17 00:00:00 2001
From: Akshat Gandhi <54901287+AkshatG6@users.noreply.github.com>
Date: Mon, 15 Sep 2025 13:26:04 -0700
Subject: [PATCH 5/8] Reverted private keyword for the class extension in
 GoogleSignInAuthenticator

---
 .../Shared/Services/GoogleSignInAuthenticator.swift             | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift b/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift
index a2f39a41..3310826d 100644
--- a/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift
+++ b/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift
@@ -149,7 +149,7 @@ final class GoogleSignInAuthenticator: ObservableObject {
 
 // MARK: Parse nonce from JWT ID Token
 
-extension GoogleSignInAuthenticator {
+private extension GoogleSignInAuthenticator {
   func decodeNonce(fromJWT jwt: String) -> String? {
     let segments = jwt.components(separatedBy: ".")
     guard let parts = decodeJWTSegment(segments[1]),

From 88e8caaaeb3de33bb171cd3c790cb3fcc4b8a72c Mon Sep 17 00:00:00 2001
From: Akshat Gandhi <54901287+AkshatG6@users.noreply.github.com>
Date: Mon, 15 Sep 2025 15:32:29 -0700
Subject: [PATCH 6/8] Updated styling and spacing for better readability

---
 .../Services/GoogleSignInAuthenticator.swift  |  2 +-
 .../ViewModels/AuthenticationViewModel.swift  | 64 +++++++++----------
 .../iOS/UserProfileView.swift                 |  2 +-
 .../macOS/UserProfileView.swift               |  2 +-
 4 files changed, 34 insertions(+), 36 deletions(-)

diff --git a/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift b/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift
index 3310826d..88d00f2e 100644
--- a/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift
+++ b/Samples/Swift/DaysUntilBirthday/Shared/Services/GoogleSignInAuthenticator.swift
@@ -71,7 +71,7 @@ final class GoogleSignInAuthenticator: ObservableObject {
     GIDSignIn.sharedInstance.signIn(
       withPresenting: presentingWindow,
       tokenClaims: tokenClaims
-      ) { signInResult, error in
+    ) { signInResult, error in
       guard let signInResult = signInResult else {
         print("Error! \(String(describing: error))")
         return
diff --git a/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift b/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
index fdc65fb5..cd13da32 100644
--- a/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
+++ b/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
@@ -26,7 +26,6 @@ final class AuthenticationViewModel: ObservableObject {
     return GoogleSignInAuthenticator(authViewModel: self)
   }
 
-  // 3. Change authTime to a computed property
   var authTime: Date? {
     switch state {
     case .signedIn(let user):
@@ -83,47 +82,46 @@ final class AuthenticationViewModel: ObservableObject {
   }
   
   var formattedAuthTimeString: String? {
-          guard let date = authTime else { return nil }
-          let formatter = DateFormatter()
-          formatter.dateFormat = "MM/dd/yyyy"
-          return formatter.string(from: date)
+    guard let date = authTime else { return nil }
+    let formatter = DateFormatter()
+    formatter.dateFormat = "MMM d, yyyy 'at' h:mm a"
+    return formatter.string(from: date)
   }
 }
 
 private extension AuthenticationViewModel {
-    func decodeAuthTime(fromJWT jwt: String) -> Date? {
-        let segments = jwt.components(separatedBy: ".")
-        guard segments.count > 1,
-              let parts = decodeJWTSegment(segments[1]),
-              let authTimeInterval = parts["auth_time"] as? TimeInterval else {
-            return nil
-        }
-        return Date(timeIntervalSince1970: authTimeInterval)
+  func decodeAuthTime(fromJWT jwt: String) -> Date? {
+    let segments = jwt.components(separatedBy: ".")
+    guard let parts = decodeJWTSegment(segments[1]),
+          let authTimeInterval = parts["auth_time"] as? TimeInterval else {
+      return nil
     }
+    return Date(timeIntervalSince1970: authTimeInterval)
+  }
 
-    func decodeJWTSegment(_ segment: String) -> [String: Any]? {
-        guard let segmentData = base64UrlDecode(segment),
-              let segmentJSON = try? JSONSerialization.jsonObject(with: segmentData, options: []),
-              let payload = segmentJSON as? [String: Any] else {
-            return nil
-        }
-        return payload
+  func decodeJWTSegment(_ segment: String) -> [String: Any]? {
+    guard let segmentData = base64UrlDecode(segment),
+          let segmentJSON = try? JSONSerialization.jsonObject(with: segmentData, options: []),
+          let payload = segmentJSON as? [String: Any] else {
+      return nil
     }
+    return payload
+  }
+  
+  func base64UrlDecode(_ value: String) -> Data? {
+    var base64 = value
+      .replacingOccurrences(of: "-", with: "+")
+      .replacingOccurrences(of: "_", with: "/")
 
-    func base64UrlDecode(_ value: String) -> Data? {
-        var base64 = value
-            .replacingOccurrences(of: "-", with: "+")
-            .replacingOccurrences(of: "_", with: "/")
-
-        let length = Double(base64.lengthOfBytes(using: String.Encoding.utf8))
-        let requiredLength = 4 * ceil(length / 4.0)
-        let paddingLength = requiredLength - length
-        if paddingLength > 0 {
-            let padding = "".padding(toLength: Int(paddingLength), withPad: "=", startingAt: 0)
-            base64 = base64 + padding
-        }
-        return Data(base64Encoded: base64, options: .ignoreUnknownCharacters)
+    let length = Double(base64.lengthOfBytes(using: String.Encoding.utf8))
+    let requiredLength = 4 * ceil(length / 4.0)
+    let paddingLength = requiredLength - length
+    if paddingLength > 0 {
+      let padding = "".padding(toLength: Int(paddingLength), withPad: "=", startingAt: 0)
+      base64 = base64 + padding
     }
+    return Data(base64Encoded: base64, options: .ignoreUnknownCharacters)
+  }
 }
 
 extension AuthenticationViewModel {
diff --git a/Samples/Swift/DaysUntilBirthday/iOS/UserProfileView.swift b/Samples/Swift/DaysUntilBirthday/iOS/UserProfileView.swift
index 929ec3a2..256b777b 100644
--- a/Samples/Swift/DaysUntilBirthday/iOS/UserProfileView.swift
+++ b/Samples/Swift/DaysUntilBirthday/iOS/UserProfileView.swift
@@ -36,7 +36,7 @@ struct UserProfileView: View {
                 .font(.headline)
               Text(userProfile.email)
               if let authTimeString = authViewModel.formattedAuthTimeString {
-                  Text("Last sign-in date: \(authTimeString)")
+                Text("Last sign-in date: \(authTimeString)")
               }
             }
           }
diff --git a/Samples/Swift/DaysUntilBirthday/macOS/UserProfileView.swift b/Samples/Swift/DaysUntilBirthday/macOS/UserProfileView.swift
index c19a716f..3fddc744 100644
--- a/Samples/Swift/DaysUntilBirthday/macOS/UserProfileView.swift
+++ b/Samples/Swift/DaysUntilBirthday/macOS/UserProfileView.swift
@@ -20,7 +20,7 @@ struct UserProfileView: View {
                 .font(.headline)
               Text(userProfile.email)
               if let authTimeString = authViewModel.formattedAuthTimeString {
-                  Text("Last sign-in date: \(authTimeString)")
+                Text("Last sign-in date: \(authTimeString)")
               }
             }
           }

From 20c52ba8a4f90e7c9f1091ec2aa6e9ec7cada6c9 Mon Sep 17 00:00:00 2001
From: Akshat Gandhi <54901287+AkshatG6@users.noreply.github.com>
Date: Mon, 15 Sep 2025 15:42:32 -0700
Subject: [PATCH 7/8] Added comments to AuthenticationViewModel to improve
 readability

---
 .../Shared/ViewModels/AuthenticationViewModel.swift             | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift b/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
index cd13da32..68f85972 100644
--- a/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
+++ b/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
@@ -26,6 +26,8 @@ final class AuthenticationViewModel: ObservableObject {
     return GoogleSignInAuthenticator(authViewModel: self)
   }
 
+  /// The user's `auth_time` as found in `idToken`.
+  /// - note: If the user is logged out, then this will default to nil.
   var authTime: Date? {
     switch state {
     case .signedIn(let user):

From fb6eef3c281577afc7d6704137625eaf79add226 Mon Sep 17 00:00:00 2001
From: Akshat Gandhi <54901287+AkshatG6@users.noreply.github.com>
Date: Mon, 15 Sep 2025 15:50:28 -0700
Subject: [PATCH 8/8] Added markdown to the comment in AuthenticationViewModel

---
 .../Shared/ViewModels/AuthenticationViewModel.swift             | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift b/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
index 68f85972..b528fc68 100644
--- a/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
+++ b/Samples/Swift/DaysUntilBirthday/Shared/ViewModels/AuthenticationViewModel.swift
@@ -27,7 +27,7 @@ final class AuthenticationViewModel: ObservableObject {
   }
 
   /// The user's `auth_time` as found in `idToken`.
-  /// - note: If the user is logged out, then this will default to nil.
+  /// - note: If the user is logged out, then this will default to `nil`.
   var authTime: Date? {
     switch state {
     case .signedIn(let user):