[Vertex AI] Add code snippets for use in docs

FirebaseVertexAI/Tests/Unit/Snippets/FirebaseAppSnippetsUtil.swift

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+// Copyright 2024 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 FirebaseCore
+import Foundation
+import XCTest
+
+extension FirebaseApp {
+  static let projectIDEnvVar = "PROJECT_ID"
+  static let appIDEnvVar = "APP_ID"
+  static let apiKeyEnvVar = "API_KEY"
+
+  static func configureForSnippets() throws {
+    let environment = ProcessInfo.processInfo.environment
+    guard let projectID = environment[projectIDEnvVar] else {
+      throw XCTSkip("No Firebase Project ID specified in environment variable \(projectIDEnvVar).")
+    }
+    guard let appID = environment[appIDEnvVar] else {
+      throw XCTSkip("No Google App ID specified in environment variable \(appIDEnvVar).")
+    }
+    guard let apiKey = environment[apiKeyEnvVar] else {
+      throw XCTSkip("No API key specified in environment variable \(apiKeyEnvVar).")
+    }
+
+    let options = FirebaseOptions(googleAppID: appID, gcmSenderID: "")
+    options.projectID = projectID
+    options.apiKey = apiKey
+
+    FirebaseApp.configure(options: options)
+    guard FirebaseApp.isDefaultAppConfigured() else {
+      XCTFail("Default Firebase app not configured.")
+      return
+    }
+  }
+}

FirebaseVertexAI/Tests/Unit/Snippets/FunctionCallingSnippets.swift

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+// Copyright 2024 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 FirebaseCore
+import FirebaseVertexAI
+import XCTest
+
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+final class FunctionCallingSnippets: XCTestCase {
+  override func setUpWithError() throws {
+    try FirebaseApp.configureForSnippets()
+  }
+
+  override func tearDown() async throws {
+    if let app = FirebaseApp.app() {
+      await app.delete()
+    }
+  }
+
+  func testFunctionCalling() async throws {
+    // This function calls a hypothetical external API that returns
+    // a collection of weather information for a given location on a given date.
+    func fetchWeather(city: String, state: String, date: String) -> JSONObject {
+      // TODO(developer): Write a standard function that would call an external weather API.
+
+      // For demo purposes, this hypothetical response is hardcoded here in the expected format.
+      return [
+        "temperature": .number(38),
+        "chancePrecipitation": .string("56%"),
+        "cloudConditions": .string("partlyCloudy"),
+      ]
+    }
+
+    let fetchWeatherTool = FunctionDeclaration(
+      name: "fetchWeather",
+      description: "Get the weather conditions for a specific city on a specific date.",
+      parameters: [
+        "location": .object(
+          properties: [
+            "city": .string(description: "The city of the location."),
+            "state": .string(description: "The US state of the location."),
+          ],
+          description: """
+          The name of the city and its state for which to get the weather. Only cities in the
+          USA are supported.
+          """
+        ),
+        "date": .string(description: """
+          The date for which to get the weather. Date must be in the format: YYYY-MM-DD.
+          """
+        ),
+      ]
+    )
+
+    // Initialize the Vertex AI service and the generative model.
+    // Use a model that supports function calling, like a Gemini 1.5 model.
+    let model = VertexAI.vertexAI().generativeModel(
+      modelName: "gemini-1.5-flash",
+      // Provide the function declaration to the model.
+      tools: [.functionDeclarations([fetchWeatherTool])]
+    )
+
+    let chat = model.startChat()
+    let prompt = "What was the weather in Boston on October 17, 2024?"
+
+    // Send the user's question (the prompt) to the model using multi-turn chat.
+    let response = try await chat.sendMessage(prompt)
+
+    var functionResponses = [FunctionResponsePart]()
+
+    // When the model responds with one or more function calls, invoke the function(s).
+    for functionCall in response.functionCalls {
+      if functionCall.name == "fetchWeather" {
+        // TODO(developer): Handle invalid arguments.
+        guard case let .object(location) = functionCall.args["location"] else { fatalError() }
+        guard case let .string(city) = location["city"] else { fatalError() }
+        guard case let .string(state) = location["state"] else { fatalError() }
+        guard case let .string(date) = functionCall.args["date"] else { fatalError() }
+
+        functionResponses.append(FunctionResponsePart(
+          name: functionCall.name,
+          response: fetchWeather(city: city, state: state, date: date)
+        ))
+      }
+      // TODO(developer): Handle other potential function calls, if any.
+    }
+
+    // Send the response(s) from the function back to the model so that the model can use it
+    // to generate its final response.
+    let finalResponse = try await chat.sendMessage(
+      [ModelContent(role: "function", parts: functionResponses)]
+    )
+
+    // Log the text response.
+    print(finalResponse.text ?? "No text in response.")
+  }
+}

FirebaseVertexAI/Tests/Unit/Snippets/StructuredOutputSnippets.swift

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+// Copyright 2024 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 FirebaseCore
+import FirebaseVertexAI
+import XCTest
+
+@available(iOS 15.0, macOS 12.0, macCatalyst 15.0, tvOS 15.0, watchOS 8.0, *)
+final class StructuredOutputSnippets: XCTestCase {
+  override func setUpWithError() throws {
+    try FirebaseApp.configureForSnippets()
+  }
+
+  override func tearDown() async throws {
+    if let app = FirebaseApp.app() {
+      await app.delete()
+    }
+  }
+
+  func testStructuredOutputJSONBasic() async throws {
+    // Provide a JSON schema object using a standard format.
+    // Later, pass this schema object into `responseSchema` in the generation config.
+    let jsonSchema = Schema.object(
+      properties: [
+        "characters": Schema.array(
+          items: .object(
+            properties: [
+              "name": .string(),
+              "age": .integer(),
+              "species": .string(),
+              "accessory": .enumeration(values: ["hat", "belt", "shoes"]),
+            ],
+            optionalProperties: ["accessory"]
+          )
+        ),
+      ]
+    )
+
+    // Initialize the Vertex AI service and the generative model.
+    // Use a model that supports `responseSchema`, like one of the Gemini 1.5 models.
+    let model = VertexAI.vertexAI().generativeModel(
+      modelName: "gemini-1.5-flash",
+      // In the generation config, set the `responseMimeType` to `application/json`
+      // and pass the JSON schema object into `responseSchema`.
+      generationConfig: GenerationConfig(
+        responseMIMEType: "application/json",
+        responseSchema: jsonSchema
+      )
+    )
+
+    let prompt = "For use in a children's card game, generate 10 animal-based characters."
+
+    let response = try await model.generateContent(prompt)
+    print(response.text ?? "No text in response.")
+  }
+
+  func testStructuredOutputEnumBasic() async throws {
+    // Provide an enum schema object using a standard format.
+    // Later, pass this schema object into `responseSchema` in the generation config.
+    let enumSchema = Schema.enumeration(values: ["drama", "comedy", "documentary"])
+
+    // Initialize the Vertex AI service and the generative model.
+    // Use a model that supports `responseSchema`, like one of the Gemini 1.5 models.
+    let model = VertexAI.vertexAI().generativeModel(
+      modelName: "gemini-1.5-flash",
+      // In the generation config, set the `responseMimeType` to `text/x.enum`
+      // and pass the enum schema object into `responseSchema`.
+      generationConfig: GenerationConfig(
+        responseMIMEType: "text/x.enum",
+        responseSchema: enumSchema
+      )
+    )
+
+    let prompt = """
+    The film aims to educate and inform viewers about real-life subjects, events, or people.
+    It offers a factual record of a particular topic by combining interviews, historical footage,
+    and narration. The primary purpose of a film is to present information and provide insights
+    into various aspects of reality.
+    """
+
+    let response = try await model.generateContent(prompt)
+    print(response.text ?? "No text in response.")
+  }
+}