docs: getting started for auth firebaseUI using SwiftUI

[russellwheatley]

• Wrote a getting started document for the latest FirebaseUI iOS SwiftUI to mirror closely the previous: https://firebase.google.com/docs/auth/ios/firebaseui

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a new, dedicated getting started guide for FirebaseUI authentication tailored for SwiftUI applications. The document provides developers with clear, step-by-step instructions to integrate and configure various authentication methods, enabling them to quickly implement modern, SwiftUI-first sign-in experiences.

Highlights

• New SwiftUI Getting Started Guide: A comprehensive guide for integrating FirebaseUI authentication with SwiftUI applications has been added, covering setup, various sign-in methods, and customization options.
• Swift Package Manager Integration: Detailed instructions are provided for adding FirebaseUI for SwiftUI via Swift Package Manager, including core and provider-specific packages.
• Multi-Provider Authentication Setup: The guide outlines how to configure and register multiple authentication providers such as Email/Password, Apple, Google, Facebook, Phone, Twitter, and generic OAuth/OIDC.
• SwiftUI-First Sign-In Flows: Developers are guided on using AuthPickerView for opinionated default UI flows and AuthService for more custom authentication experiences.

🧠 New Feature in Public Preview: You can now enable Memory to help Gemini Code Assist learn from your team's feedback. This makes future code reviews more consistent and personalized to your project's style. Click here to enable Memory in your admin console.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for GitHub and other Google products, sign up here.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

The pull request introduces a new GETTING_STARTED.md documentation file for FirebaseUI for SwiftUI, detailing setup, authentication provider configuration, and usage examples. Review comments identify several issues and improvement opportunities within the provided Swift code snippets: a critical compilation error in the AppDelegate's application(_:open:options:) function due to a missing return statement, a potential runtime crash from force-unwrapping Bundle.main.bundleIdentifier, and a hardcoded APNS token type (.prod) that should ideally be conditional (.sandbox for debug builds). Additionally, the review suggests consolidating duplicated and incomplete AppDelegate examples to improve clarity and prevent confusion.