[Vertex AI] Use ephemeral URLSession config on iOS 18.4 sim (#14696)

Author: andrewheard

.github/workflows/vertexai.yml

@@ -47,22 +47,22 @@ jobs:
             xcode: Xcode_16.2
             target: iOS
           - os: macos-15
-            xcode: Xcode_16.2
+            xcode: Xcode_16.3
             target: iOS
           - os: macos-15
-            xcode: Xcode_16.2
+            xcode: Xcode_16.3
             target: tvOS
           - os: macos-15
-            xcode: Xcode_16.2
+            xcode: Xcode_16.3
             target: macOS
           - os: macos-15
-            xcode: Xcode_16.2
+            xcode: Xcode_16.3
             target: watchOS
           - os: macos-15
-            xcode: Xcode_16.2
+            xcode: Xcode_16.3
             target: catalyst
           - os: macos-15
-            xcode: Xcode_16.2
+            xcode: Xcode_16.3
             target: visionOS
     runs-on: ${{ matrix.os }}
     needs: spm-package-resolved
@@ -98,7 +98,7 @@ jobs:
         os: [macos-15]
         include:
           - os: macos-15
-            xcode: Xcode_16.2
+            xcode: Xcode_16.3
     runs-on: ${{ matrix.os }}
     needs: spm-package-resolved
     env:
@@ -137,11 +137,11 @@ jobs:
             swift_version: 5.9
             warnings:
           - os: macos-15
-            xcode: Xcode_16.2
+            xcode: Xcode_16.3
             swift_version: 5.9
             warnings:
           - os: macos-15
-            xcode: Xcode_16.2
+            xcode: Xcode_16.3
             swift_version: 6.0
             warnings:
     runs-on: ${{ matrix.os }}

FirebaseVertexAI/CHANGELOG.md

@@ -8,6 +8,8 @@
   change in backwards-incompatible ways.
 - [added] Added support for specifying the minimum and maximum number of items
   (`minItems` / `maxItems`) to generate in an array `Schema`. (#14671)
+- [fixed] Fixed an issue where network requests would fail in the iOS 18.4
+  simulator due to a `URLSession` bug introduced in Xcode 16.3. (#14677)
 
 # 11.11.0
 - [added] Emits a warning when attempting to use an incompatible model with

FirebaseVertexAI/Sources/GenAIURLSession.swift

@@ -0,0 +1,38 @@
+// 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 Foundation
+
+/// A namespace providing `URLSession` instances.
+enum GenAIURLSession {
+  /// The default `URLSession` instance for the SDK; returns `URLSession.shared` by default.
+  ///
+  /// - Important: On affected simulators (iOS 18.4+, visionOS 2.4+), this returns an ephemeral
+  ///   `URLSession` instance as a workaround for a known system bug.
+  static let `default` = {
+    #if targetEnvironment(simulator)
+      // The iOS 18.4 and visionOS 2.4 simulators (included in Xcode 16.3) contain a bug in
+      // `URLSession` causing requests to fail. The following workaround, using an ephemeral session
+      // resolves the issue. See https://developer.apple.com/forums/thread/777999 for more details.
+      //
+      // Note: This bug only impacts the simulator, not real devices, and does not impact watchOS
+      // or tvOS.
+      if #available(iOS 18.4, tvOS 100.0, watchOS 100.0, visionOS 2.4, *) {
+        return URLSession(configuration: URLSessionConfiguration.ephemeral)
+      }
+    #endif // targetEnvironment(simulator)
+
+    return URLSession.shared
+  }()
+}

FirebaseVertexAI/Sources/GenerativeModel.swift

@@ -83,7 +83,7 @@ public final class GenerativeModel: Sendable {
        toolConfig: ToolConfig? = nil,
        systemInstruction: ModelContent? = nil,
        requestOptions: RequestOptions,
-       urlSession: URLSession = .shared) {
+       urlSession: URLSession = GenAIURLSession.default) {
     self.modelName = modelName
     self.modelResourceName = modelResourceName
     self.apiConfig = apiConfig

FirebaseVertexAI/Sources/Types/Public/Imagen/ImagenModel.swift

@@ -53,7 +53,7 @@ public final class ImagenModel {
        generationConfig: ImagenGenerationConfig?,
        safetySettings: ImagenSafetySettings?,
        requestOptions: RequestOptions,
-       urlSession: URLSession = .shared) {
+       urlSession: URLSession = GenAIURLSession.default) {
     self.modelResourceName = modelResourceName
     self.apiConfig = apiConfig
     generativeAIService = GenerativeAIService(

FirebaseVertexAI/Sources/VertexAI.swift

@@ -18,7 +18,7 @@ import FirebaseCore
 import Foundation
 
 // Avoids exposing internal FirebaseCore APIs to Swift users.
-@_implementationOnly import FirebaseCoreExtension
+internal import FirebaseCoreExtension
 
 /// The Vertex AI for Firebase SDK provides access to Gemini models directly from your app.
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)

FirebaseVertexAI/Sources/VertexLog.swift

@@ -15,7 +15,7 @@
 import Foundation
 import os.log
 
-@_implementationOnly import FirebaseCoreExtension
+internal import FirebaseCoreExtension
 
 enum VertexLog {
   /// Log message codes for the Vertex AI SDK

FirebaseVertexAI/Tests/Unit/GenerativeModelTests.swift

@@ -17,7 +17,7 @@ import FirebaseAuthInterop
 import FirebaseCore
 import XCTest
 
-@testable import FirebaseVertexAI
+@testable public import FirebaseVertexAI
 
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 final class GenerativeModelTests: XCTestCase {
@@ -1690,8 +1690,7 @@ struct AppCheckErrorFake: Error {}
 
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
 extension SafetyRating: Swift.Comparable {
-  public static func < (lhs: FirebaseVertexAI.SafetyRating,
-                        rhs: FirebaseVertexAI.SafetyRating) -> Bool {
+  public static func < (lhs: SafetyRating, rhs: SafetyRating) -> Bool {
     return lhs.category.rawValue < rhs.category.rawValue
   }
 }

FirebaseVertexAI/Tests/Unit/VertexComponentTests.swift

@@ -13,11 +13,10 @@
 // limitations under the License.
 
 @preconcurrency import FirebaseCore
+internal import FirebaseCoreExtension
 import Foundation
 import XCTest
 
-@_implementationOnly import FirebaseCoreExtension
-
 @testable import FirebaseVertexAI
 
 @available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)