GTMOAuth2

The Google Toolbox for Mac OAuth 2 Controllers make it easy for Cocoa applications to sign in to services using OAuth 2 for authentication and authorization.

Source on Google Code

Features include:

• Complete embedded user interface using WebKit
• Works with Google APIs and with any standard OAuth 2 provider
• Handles sign-in, keychain storage of authorization token, and authorizing of requests
• Independent of other projects

Introduction

BecomingAContributor