IOS architecture consists of four layers. It has an intermediate layer between the applications and the hardware so they do not communicate directly. The higher layers of iOS provide the user interface and sophisticated graphics and the lower layers of iOS provide the basic services.
The layered architecture of iOS is given as below:
Core OS Layer:
The Core OS is the lower layer of iOS architecture levels and the one closest to the device hardware, being perched right on top of it. This layer provides many of the low-level features necessary that some of the services in the higher levels need to work.
- Core Bluetooth Framework.
- Accelerate Framework.
- External Accessory Framework.
- Security Services framework.
- Local Authentication framework.
Core Services Layer:
This Core Services layer provides an abstraction over the services provided in the Core OS layer. This layer provides fundamental access to iPhone OS services. Some of the Important Frameworks available in the core services layers are as below:
- Address book framework: provides access to a contacts database of the user.
- Cloud Kit framework: using this framework, moving data between your app and iCloud.
- Core data Framework: It is used to managing the data model of a Model View Controller app.
- Core Foundation framework: It gives fundamental data management and service features for iOS apps.
- Core Location framework: It gives the location and heading information of various apps.
- Core Motion Framework: Used to access all motion-based data available on a device.
- Healthkit framework: This is a new framework that handling health-related information of the user.
- Homekit framework: This is a new framework for talking with and controlling connected devices in a user’s home.
- Social framework: It is a simple interface for accessing the user’s social media accounts.
- StoreKit framework: It gives support for the buying of content and services from inside your iOS apps, a feature is known asIn-App Purchase.
Media Layer:
The Media layer makes the picture on your iOS device crisp and the song you’re listening to sound clear. This layer handled all of the audio, video and graphic frameworks that help deliver a dynamic multimedia experience for the mobile user.
Graphics Framework:
- UIKit Graphics: It provides support for designing images and also used for animating the content of your views.
- Core Graphics framework: It provides support for 2D vector and image-based rendering and is the native drawing engine for iOS apps.
- Core Animation: It optimizes the animation experience of your apps.
- Core Images: It gives advanced support for controlling video and motionless images in a nondestructive way.
- OpenGL ES and GLKit: It manages advanced 2D and 3D rendering by hardware-accelerated interfaces.
Audio Framework:
- Media Player Framework: It gives simple to use to a user’s iTunes library and support for playing playlists.
- OpenAL: It is an industry-standard technology for providing audio.
- AV Foundation: It handles the recording and playback of audio and video.
Video Framework:
- Core Media: It describes the low-level interfaces and data types for operating media.
- AV Kit: It gives a collection of easy to use interfaces for presenting video.
- AV Foundation: It gives advanced video playback and recording capability.
Cocoa Touch Layer:
The Cocoa Touch layer is the upper layer of the iOS architecture. This layer defines the basic application infrastructure and provides several vital technologies, such as multitasking and touch-based input. It provides the following framework:
- EventKit framework: It shows the standard system interfaces using view controllers for viewing and changing calendar related events.
- GameKit Framework: It allows users to share their game-related information online using Game Center.
- iAd Framework: It allows you to deliver banner-based advertisements from your app.
- MapKit Framework: It provides a scrollable map that you can include in your user interface of the app.
- PushKitFramework: It provides registration support for VoIP apps.
- Twitter Framework: It supports a UI for generating tweets and support for creating URLs to access the Twitter service.
- UIKit Framework: It gives a vital infrastructure for applying graphical, event-driven apps in iOS.