IOS API Overview

Introduction to IOS APIs

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Apple's iOS API has changed a lot between different versions, and this book is based on iOS 6. In this section, we describe what APIs are available in iOS 6, how to use the Help documentation for these APIs, and how to use the official case.
2.6.1 API Overview
The overall architecture of iOS, shown in Figure 2-40, is divided into 4 layers of--cocoa touch layer, media layer, core services layer and core OS layer, which provides an overview of these 4 layers.

Figure 2-40 iOS Overall architecture diagram
1. Cocoa Touch Layer
This layer provides basic system services for building iOS apps (such as multitasking, touch input and push notifications, etc.) and key frameworks (see table 2-3).

Table 2-3 Cocoa Touch layer included frame

Framework	Prefix	Description
Address Book UI	Ab	Access User's contact information
Event Kit UI	EK	Accessing the user's calendar event data
Game Kit	Gk	Provides an API for peer-to-peer network communication
Iad	AD	Embed ads in your app
Map Kit	Mk	Embed maps and geographic information encodings in your application
Message UI	Mf	Provides APIs related to sending e-mail
Twitter	TW	Provides an interface for sending Twitter
UIKit	Ui	Providing UI Classes

2. Media Layer
The media layer provides graphics, audio, video, and airplay technologies, including a framework as shown in table 2-4.

Table 2-4 The media layer includes the framework

Framework	Prefix	Description
Assets Library	AL	An interface that provides access to the user's pictures and videos
Audiotoolbox	Audio	Record or play audio, audio streams, and format conversions
AudioUnit	Audio,au	Provides use of built-in audio unit services, as well as audio processing modules
AV Foundation	Av	Provides a objective-c interface for playing and recording audio and video
Core Audio	Audio	Provides a C-language interface for recording, making, and playing audio
Core Graphics	Cg	Quartz 2D Interface Available
Core Image	Ci	Provides an interface for manipulating video and still images
Core MIDI	Midi	Provides APIs for processing low-level MIDI data
Core Text	Ct	Simple, efficient C-language interface for rendering text and working with fonts
Core Video	CV	Provides APIs for processing audio and video
Image I/O	Cg	Contains some read/write image data classes
Glkit	Glk	Contains OBJECTIVE-C utility classes for building complex OpenGL ES applications
Media Player	Mp	Includes full-screen playback interface
OpenAL	AL	C-Language interface with OpenAL (cross-platform audio)
OpenGL ES	Eagl,gl	C-Language interface with OpenGL ES (cross-platform 2d/3d Graphics library)
Quartz Core	Ca	Provides an animated interface class

3. Core services Layer
This layer provides technologies such as icloud, in-app purchases, SQLite databases, and XML support, including the main frameworks shown in table 2-5.

Table 2-5 Core services layer includes the framework

Framework	Prefix	Description
Accounts	AC	Twitter account for accessing users (this API is available after IOS 5)
AddressBook	Ab	Access User's contact information
Adsupport	As	Get IAD ad ID
Cfnetwork	Cf	Provides an API to access Wi-Fi networks and cellular networks
Core Data	Ns	Provides an ORM interface for managing application data
Corefoundation	Cf	It is the most basic framework in iOS development, including datasets
Core Location	Cl	API to provide location services
CoreMedia	Cm	Provides the underlying media type used by the AV Foundation framework. Precise control of the creation and presentation of audio or video
Coremotion	Cm	Receive and process gravity accelerometers and other motion events
Coretelephony	Ct	Provides an API to access basic information about a phone
Event Kit	EK	Accessing the user's calendar event data
Foundation	Ns	Provides OBJECTIVE-C encapsulation for many features of the core Foundation framework and is the most basic framework for OBJECTIVE-C
Mobilecoreservices	Ut	Define the underlying type used by the uniform type identifier (UTI)
Newsstand Kit	Nk	API interface for downloading magazines and news in the background (IOS 5 only)
Pass Kit	Pk	API to access various coupons (IOS 6 is available after this API)
QuickLook	Ql	The framework can preview file content that cannot be viewed directly, such as opening a PDF file
Social	Sl	Social network access API available in China with Sina Weibo API (this API is available after IOS 6)
Store Kit	Sk	Provides money transactions to handle application-built charges
SystemConfiguration	Sc	Used to determine the network configuration of a device (for example, using the framework to determine whether Wi-Fi or cellular connections are in use), or to determine whether a host service can be used

4. Core OS Layer
This layer provides some low-level functionality, which is generally not used directly in development. The main framework included in this layer is shown in table 2-6.
Table 2-6 Core OS layer included framework

Framework	Prefix	Description
Accelerate	AC	Accessing the Gravity Accelerometer API
Core Bluetooth	Cb	Accessing the low energy Bluetooth device API
External Accessory	Ea	Accessing the Peripheral Accessory API interface
Generic Security Services	Gss	Provide a set of security-related services
Security	Cssm,sec	Manage certificates, public keys, private keys, and security trust policy APIs

IOS API Overview