feat(sample): add full-customization example covering every auth screen

FirebaseSwiftUI/FirebaseAuthSwiftUI/Sources/Exports.swift

@@ -0,0 +1,17 @@
+// Copyright 2025 Google LLC
+//
+// 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.
+
+// FirebaseAuthUIComponents is not a library product, so re-export it to make
+// AuthTextFieldStyle and AuthTypography reachable from `import FirebaseAuthSwiftUI`.
+@_exported import FirebaseAuthUIComponents

FirebaseSwiftUI/FirebaseAuthSwiftUI/Sources/Services/AuthService.swift

@@ -33,6 +33,24 @@ public protocol AuthProviderUI {
   var provider: AuthProviderSwift { get }
 }
 
+/// Lets ``AuthService/triggerSignIn(for:)`` start sign-in for a provider whose flow doesn't
+/// produce a credential, such as phone or a custom flow that presents its own screens.
+///
+/// Adopt it on a custom provider so a custom method picker layout can start its sign-in through
+/// ``AuthMethodPickerState/select``. Otherwise, start sign-in from the provider's own button.
+///
+/// Example:
+/// ```swift
+/// extension MyProviderAuthUI: AuthProviderAction {
+///   func triggerAction() async throws {
+///     try await startMySignInFlow()
+///   }
+/// }
+/// ```
+public protocol AuthProviderAction: AuthProviderUI {
+  @MainActor func triggerAction() async throws
+}
+
 public enum AuthenticationState {
   case unauthenticated
   case authenticating
@@ -184,6 +202,40 @@ public final class AuthService {
     providers.append(providerWithButton)
   }
 
+  /// The providers registered with ``registerProvider(providerWithButton:)``, in registration
+  /// order. Email and email-link sign-in aren't included.
+  public var registeredProviders: [AuthProviderUI] {
+    providers
+  }
+
+  /// Starts sign-in with `provider` without rendering its button.
+  ///
+  /// ``AuthProviderAction`` providers run ``AuthProviderAction/triggerAction()``, in which case
+  /// this returns `nil`. Other credential-based providers sign in through ``signIn(_:)``.
+  /// Any other provider throws ``AuthServiceError/providerAuthenticationFailed(_:)``.
+  public func triggerSignIn(for provider: AuthProviderUI) async throws -> SignInOutcome? {
+    if let actionProvider = provider as? AuthProviderAction {
+      try await actionProvider.triggerAction()
+      return nil
+    }
+    if let credentialProvider = provider.provider as? CredentialAuthProviderSwift {
+      return try await signIn(credentialProvider)
+    }
+    throw AuthServiceError.providerAuthenticationFailed(
+      "\(provider.displayName) doesn't support starting sign-in programmatically. " +
+        "Adopt AuthProviderAction on the provider, or start sign-in from its own button."
+    )
+  }
+
+  /// Runs the email-link sign-in action, the same as the stock email-link button.
+  func selectEmailLink() {
+    if let callback = emailLinkSignInCallback {
+      callback()
+    } else {
+      navigator.push(.emailLink)
+    }
+  }
+
   public func renderButtons(spacing: CGFloat = 16) -> AnyView {
     AnyView(
       VStack(spacing: spacing) {
@@ -193,11 +245,7 @@ public final class AuthService {
             style: .email,
             accessibilityId: "sign-in-with-email-link-button"
           ) {
-            if let callback = self.emailLinkSignInCallback {
-              callback()
-            } else {
-              self.navigator.push(.emailLink)
-            }
+            self.selectEmailLink()
           }
         }
         ForEach(providers, id: \.id) { provider in

FirebaseSwiftUI/FirebaseAuthSwiftUI/Sources/Views/AuthCTAButtonModifier.swift

@@ -0,0 +1,134 @@
+// Copyright 2025 Google LLC
+//
+// 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 FirebaseAuthUIComponents
+import SwiftUI
+
+/// Styling configuration for the primary call-to-action buttons used throughout the auth flow
+/// (sign in, send code, update password, etc). All fields default to `nil`, in which case
+/// today's exact appearance is unchanged — including `backgroundColor`, which otherwise already
+/// follows the environment's `.tint()` via `.buttonStyle(.borderedProminent)`; setting it here
+/// overrides that for CTA buttons specifically, without affecting `.tint()` elsewhere.
+public struct AuthCTAButtonStyle: Sendable {
+  public var backgroundColor: Color?
+  public var contentColor: Color?
+  public var shape: ButtonBorderShape?
+  public var font: Font?
+
+  public init(backgroundColor: Color? = nil,
+              contentColor: Color? = nil,
+              shape: ButtonBorderShape? = nil,
+              font: Font? = nil) {
+    self.backgroundColor = backgroundColor
+    self.contentColor = contentColor
+    self.shape = shape
+    self.font = font
+  }
+
+  public static let `default` = AuthCTAButtonStyle()
+}
+
+private struct AuthCTAButtonStyleKey: EnvironmentKey {
+  static let defaultValue: AuthCTAButtonStyle = .default
+}
+
+public extension EnvironmentValues {
+  var authCTAButtonStyle: AuthCTAButtonStyle {
+    get { self[AuthCTAButtonStyleKey.self] }
+    set { self[AuthCTAButtonStyleKey.self] = newValue }
+  }
+}
+
+/// Applies `.buttonStyle(.borderedProminent)` plus the colors/shape/font from the environment's
+/// ``AuthCTAButtonStyle``, in place of a bare `.buttonStyle(.borderedProminent)` call. Unset
+/// values leave the inherited shape, tint and font alone. When `style.font` is unset, the label
+/// uses ``AuthTypography``'s custom font if one is set.
+struct AuthCTAButtonModifier: ViewModifier {
+  @Environment(\.authCTAButtonStyle) private var style
+
+  func body(content: Content) -> some View {
+    Group {
+      if let contentColor = style.contentColor {
+        content.foregroundStyle(contentColor)
+      } else {
+        content
+      }
+    }
+    .buttonStyle(.borderedProminent)
+    .modifier(CTAShapeModifier(shape: style.shape))
+    .modifier(CTATintModifier(tint: style.backgroundColor))
+    .modifier(CTAFontModifier(explicitFont: style.font))
+  }
+}
+
+// Each modifier below only applies a value when one is set, so an unset style leaves whatever
+// the app set higher up (shape, tint, font) in effect, as before theming.
+
+private struct CTAShapeModifier: ViewModifier {
+  let shape: ButtonBorderShape?
+
+  func body(content: Content) -> some View {
+    if let shape {
+      content.buttonBorderShape(shape)
+    } else {
+      content
+    }
+  }
+}
+
+private struct CTATintModifier: ViewModifier {
+  let tint: Color?
+
+  func body(content: Content) -> some View {
+    if let tint {
+      content.tint(tint)
+    } else {
+      content
+    }
+  }
+}
+
+private struct CTAFontModifier: ViewModifier {
+  let explicitFont: Font?
+
+  func body(content: Content) -> some View {
+    if let explicitFont {
+      content.font(explicitFont)
+    } else {
+      content.authCustomFont(.body)
+    }
+  }
+}
+
+extension View {
+  /// Applies the auth flow's primary call-to-action button styling, reading colors/shape/font
+  /// from the environment's ``AuthCTAButtonStyle`` (set via `.authCTAButtonStyle(_:)`).
+  func authCTAButtonStyle() -> some View {
+    modifier(AuthCTAButtonModifier())
+  }
+}
+
+public extension View {
+  /// Sets the ``AuthCTAButtonStyle`` used by every CTA button in this view's subtree.
+  ///
+  /// ```swift
+  /// AuthPickerView { ... }
+  ///   .authCTAButtonStyle(
+  ///     AuthCTAButtonStyle(backgroundColor: theme.colors.tint, contentColor: .white, shape: .capsule)
+  ///   )
+  /// ```
+  func authCTAButtonStyle(_ style: AuthCTAButtonStyle) -> some View {
+    environment(\.authCTAButtonStyle, style)
+  }
+}