Add code snippets for controlled generation (#188)

Author: andrewheard

samples/ControlledGeneration.swift

@@ -0,0 +1,89 @@
+// 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 GoogleGenerativeAI
+import XCTest
+
+// Set up your API Key
+// ====================
+// To use the Gemini API, you'll need an API key. To learn more, see the "Set up your API Key"
+// section in the Gemini API quickstart:
+// https://ai.google.dev/gemini-api/docs/quickstart?lang=swift#set-up-api-key
+
+@available(iOS 15.0, macCatalyst 15.0, *)
+final class ControlledGenerationSnippets: XCTestCase {
+  override func setUpWithError() throws {
+    try XCTSkipIf(
+      APIKey.default.isEmpty,
+      "`\(APIKey.apiKeyEnvVar)` environment variable not set."
+    )
+  }
+
+  func testJSONControlledGeneration() async throws {
+    // [START json_controlled_generation]
+    let jsonSchema = Schema(
+      type: .array,
+      description: "List of recipes",
+      items: Schema(
+        type: .object,
+        properties: [
+          "recipeName": Schema(type: .string, description: "Name of the recipe", nullable: false),
+        ],
+        requiredProperties: ["recipeName"]
+      )
+    )
+
+    let generativeModel = GenerativeModel(
+      // Specify a model that supports controlled generation like Gemini 1.5 Pro
+      name: "gemini-1.5-pro",
+      // Access your API key from your on-demand resource .plist file (see "Set up your API key"
+      // above)
+      apiKey: APIKey.default,
+      generationConfig: GenerationConfig(
+        responseMIMEType: "application/json",
+        responseSchema: jsonSchema
+      )
+    )
+
+    let prompt = "List a few popular cookie recipes."
+    let response = try await generativeModel.generateContent(prompt)
+    if let text = response.text {
+      print(text)
+    }
+    // [END json_controlled_generation]
+  }
+
+  func testJSONNoSchema() async throws {
+    // [START json_no_schema]
+    let generativeModel = GenerativeModel(
+      name: "gemini-1.5-flash",
+      // Access your API key from your on-demand resource .plist file (see "Set up your API key"
+      // above)
+      apiKey: APIKey.default,
+      generationConfig: GenerationConfig(responseMIMEType: "application/json")
+    )
+
+    let prompt = """
+    List a few popular cookie recipes using this JSON schema:
+
+    Recipe = {'recipeName': string}
+    Return: Array<Recipe>
+    """
+    let response = try await generativeModel.generateContent(prompt)
+    if let text = response.text {
+      print(text)
+    }
+    // [END json_no_schema]
+  }
+}