The Accounts framework provides access to user accounts stored in the Accounts database. An account stores the login credentials of a particular service, such as Twitter, that can be used as authentication for the service. By implementing the Accounts framework into your app, you do not need to be responsible for storing account logins yourself. Instead, the user can grant access for your app to use their account login credentials, bypassing the need to type their username and password. If no account for a particular service exists in the user’s Accounts database, you can let them create and save an account from within your app.

The Address Book framework provides access to a centralized contacts database, called the Address Book database, that stores a user’s contacts. Applications such as Mail and Messages use this database to present information about known and unknown persons.

The AV Foundation framework provides an Objective-C interface for managing and playing audio-visual media in iOS and OS X applications.

The Core Bluetooth framework provides the classes needed for your iOS and Mac apps to communicate with devices that are equipped with Bluetooth low energy wireless technology.

Core Foundation is a framework that provides fundamental software services useful to application services, application environments, and to applications themselves. Core Foundation also provides abstractions for common data types, facilitates internationalization with Unicode string storage, and offers a suite of utilities such as plug-in support, XML property lists, URL resource access, and preferences.

Core Image is an image processing and analysis technology designed to provide near real-time processing for still and video images.

The Core Location framework lets you determine the current location or heading associated with a device. The framework uses the available hardware to determine the user’s position and heading. You use the classes and protocols in this framework to configure and schedule the delivery of location and heading events. You can also use it to define geographic regions and monitor when the user crosses the boundaries of those regions. In iOS, you can also define a region around a Bluetooth beacon.

Use the Core Telephony framework to obtain information about a user’s home cellular service provider—that is, the provider with whom the user has an account. Carriers can use this information to write applications that provide services only for their own subscribers. You can also use this framework to obtain information about current cellular calls.

Core Text is an advanced, low-level technology for laying out text and handling fonts.