Add login page with Sign in with Apple and Google

sample-native-app/AuthSession.swift

@@ -0,0 +1,38 @@
+//
+//  AuthSession.swift
+//  sample-native-app
+//
+
+import Foundation
+
+enum AuthProvider: String {
+    case apple
+    case google
+
+    var displayName: String {
+        switch self {
+        case .apple: return "Apple"
+        case .google: return "Google"
+        }
+    }
+}
+
+struct SignedInUser: Equatable {
+    var displayName: String
+    var email: String?
+    var provider: AuthProvider
+}
+
+struct AuthSession: Equatable {
+    var user: SignedInUser?
+
+    var isSignedIn: Bool { user != nil }
+
+    mutating func signIn(provider: AuthProvider, displayName: String, email: String?) {
+        user = SignedInUser(displayName: displayName, email: email, provider: provider)
+    }
+
+    mutating func signOut() {
+        user = nil
+    }
+}

sample-native-app/ContentView.swift

@@ -8,17 +8,86 @@
 import SwiftUI
 
 struct ContentView: View {
+    @State private var session = AuthSession()
+
     var body: some View {
-        VStack {
-            Image(systemName: "globe")
-                .imageScale(.large)
-                .foregroundStyle(.tint)
-            Text("Hello, world!")
+        Group {
+            if let user = session.user {
+                SignedInView(user: user) {
+                    withAnimation(.easeInOut) {
+                        session.signOut()
+                    }
+                }
+                .transition(.opacity)
+            } else {
+                LoginView(session: $session)
+                    .transition(.opacity)
+            }
+        }
+        .animation(.easeInOut(duration: 0.25), value: session.isSignedIn)
+    }
+}
+
+private struct SignedInView: View {
+    let user: SignedInUser
+    let onSignOut: () -> Void
+
+    var body: some View {
+        VStack(spacing: 24) {
+            Spacer()
+
+            ZStack {
+                Circle()
+                    .fill(.tint.opacity(0.15))
+                    .frame(width: 96, height: 96)
+                Image(systemName: "checkmark.seal.fill")
+                    .font(.system(size: 48, weight: .semibold))
+                    .foregroundStyle(.tint)
+            }
+            .accessibilityHidden(true)
+
+            VStack(spacing: 8) {
+                Text("Welcome, \(user.displayName)!")
+                    .font(.title2.weight(.semibold))
+                    .multilineTextAlignment(.center)
+                    .accessibilityIdentifier("welcomeTitle")
+
+                Text("Signed in with \(user.provider.displayName)")
+                    .font(.subheadline)
+                    .foregroundStyle(.secondary)
+                    .accessibilityIdentifier("welcomeProvider")
+
+                if let email = user.email, !email.isEmpty {
+                    Text(email)
+                        .font(.footnote)
+                        .foregroundStyle(.secondary)
+                }
+            }
+
+            Spacer()
+
+            Button(role: .destructive, action: onSignOut) {
+                Text("Sign Out")
+                    .font(.headline)
+                    .frame(maxWidth: .infinity)
+                    .padding(.vertical, 14)
+            }
+            .buttonStyle(.borderedProminent)
+            .padding(.horizontal, 24)
+            .padding(.bottom, 24)
+            .accessibilityIdentifier("signOutButton")
         }
         .padding()
     }
 }
 
-#Preview {
+#Preview("Login") {
     ContentView()
 }
+
+#Preview("Signed In") {
+    SignedInView(
+        user: SignedInUser(displayName: "Ada Lovelace", email: "ada@example.com", provider: .apple),
+        onSignOut: {}
+    )
+}