Features:
- Safe, secure token storage in the iOS Keychain.
- Automatic handling of 401 responses and reauthentication.
- Scales to handle many concurrent requests in a thread-safe way.
- Stays out of your way until you need it with a simple, minimal API.
- Promotes Apple's Authentication Guidelines by "delaying sign-in as long as possible".
- Supports adapters for any number of authentication providers.
- Extensible without requiring any source modifications or pull requests.