When calling the Gemini API from your app using a Vertex AI in Firebase SDK, you can prompt the Gemini model to generate text based on a text-only input.
Other options for working with the Gemini API
Optionally experiment with an alternative "Google AI" version of the Gemini API
Get free-of-charge access (within limits and where available) using Google AI Studio and Google AI client SDKs. These SDKs should be used for prototyping only in mobile and web apps.After you're familiar with how a Gemini API works, migrate to our Vertex AI in Firebase SDKs (this documentation), which have many additional features important for mobile and web apps, like protecting the API from abuse using Firebase App Check and support for large media files in requests.
Optionally call the Vertex AI Gemini API server-side (like with Python, Node.js, or Go)
Use the server-side Vertex AI SDKs, Firebase Genkit, or Firebase Extensions for the Gemini API.
Before you begin
If you haven't already, complete the
getting started guide, which describes how to
set up your Firebase project, connect your app to Firebase, add the SDK,
initialize the Vertex AI service, and create a GenerativeModel instance.
Generate text from text-only input
You can call the Gemini API with input that includes only text. For these calls, you need to use a model that supports text-only prompts (like Gemini 2.0 Flash).
Choose whether you want to stream the response (generateContentStream) or wait
for the response until the entire result is generated (generateContent).
You can achieve faster interactions by not waiting for the entire result from the model generation, and instead use streaming to handle partial results.
This example shows how to use
generateContentStreamto stream generated text from a prompt request that includes only text:
import FirebaseVertexAI
// Initialize the Vertex AI service
let vertex = VertexAI.vertexAI()
// Create a `GenerativeModel` instance with a model that supports your use case
let model = vertex.generativeModel(modelName: "gemini-2.0-flash")
// Provide a prompt that contains text
let prompt = "Write a story about a magic backpack."
// To stream generated text output, call generateContentStream with the text input
let contentStream = try model.generateContentStream(prompt)
for try await chunk in contentStream {
if let text = chunk.text {
print(text)
}
}
Alternatively, you can wait for the entire result instead of streaming; the result is only returned after the model completes the entire generation process.
This example shows how to use
generateContent
to generate text from a prompt request that includes only text:
import FirebaseVertexAI
// Initialize the Vertex AI service
let vertex = VertexAI.vertexAI()
// Create a `GenerativeModel` instance with a model that supports your use case
let model = vertex.generativeModel(modelName: "gemini-2.0-flash")
// Provide a prompt that contains text
let prompt = "Write a story about a magic backpack."
// To generate text output, call generateContent with the text input
let response = try await model.generateContent(prompt)
print(response.text ?? "No text in response.")
Learn how to choose a model and optionally a location appropriate for your use case and app.
What else can you do?
- Learn how to count tokens before sending long prompts to the model.
- Start thinking about preparing for production, including setting up Firebase App Check to protect the Gemini API from abuse by unauthorized clients. Also, make sure to review the production checklist.
Try out other capabilities
- Build multi-turn conversations (chat).
- Generate text from multimodal prompts (including text, images, PDFs, video, and audio).
- Generate structured output (like JSON) from both text and multimodal prompts.
- Generate images from text prompts.
- Use function calling to connect generative models to external systems and information.
Learn how to control content generation
- Understand prompt design, including best practices, strategies, and example prompts.
- Configure model parameters like temperature and maximum output tokens (for Gemini) or aspect ratio and person generation (for Imagen).
- Use safety settings to adjust the likelihood of getting responses that may be considered harmful.
Learn more about the supported models
Learn about the models available for various use cases and their quotas and pricing.Give feedback about your experience with Vertex AI in Firebase