Architecture of IOS Operating System

IOS is Apple Inc.’s mobile operating system for iPhones, iPads, and other Apple mobile devices. After Android, iOS is the most popular and widely used mobile operating system.

The iOS operating system has a layered structure. It does not communicate directly. Communication will be aided by the layers between the Application Layer and the Hardware Layer. The lower level provides fundamental services upon which all applications rely, while the higher-level layers provide graphics and interface-related services. The large percentage of system interfaces come with a special package known as a framework.

A framework is a directory that contains dynamic shared libraries such as.a files, header files, images, and helper apps that are used to support the library. Each layer includes a set of frameworks that developers can use.

The layered architecture of iOS is given as follows;

• COCOA TOUCH (Application Layer)
• MEDIA Layer
• CORE SERVICES
• CORE OS

CORE OS Layer:
All IOS technologies are built on the lowest level layer, which is the Core OS layer. These technologies include:

1. Core Bluetooth Framework
2. External Accessories Framework
3. Accelerate Framework
4. Security Services Framework
5. Local Authorization Framework etc.

CORE SERVICES Layer:
The CORE SERVICES Layer contains some important frameworks that assist the iOS operating system in healing itself and providing better functionality. As shown above, it is the second lowest layer in the Architecture. This layer contains the following important frameworks:

1. Address Book Framework-
   The Address Book Framework provides access to the contact details of the user.
2. Cloud Kit Framework-
   This framework provides a medium for moving data between your app and iCloud.
3. Core Data Framework-
   This is the technology that is used for managing the data model of a Model View Controller app.
4. Core Foundation Framework-
   This framework provides data management and service features for iOS applications.
5. Core Location Framework-
   This framework helps to provide the location and heading information to the application.
6. Core Motion Framework-
   All the motion-based data on the device is accessed with the help of the Core Motion Framework.
7. Foundation Framework-
   Objective C covering too many of the features found in the Core Foundation framework.
8. HealthKit Framework-
   This framework handles the health-related information of the user.
9. HomeKit Framework-
   This framework is used for talking with and controlling connected devices with the user’s home.
10. Social Framework-
    It is simply an interface that will access users’ social media accounts.
11. StoreKit Framework-
    This framework supports for buying of contents and services from inside iOS apps.

MEDIA Layer: 
All of the system’s graphics, video, and audio technology will be enabled with the help of the media layer. The second layer of the architecture is here. The following are the various MEDIA layer frameworks:

1. ULKit Graphics-
   This framework provides support for designing images and animating the view content.
2. Core Graphics Framework-
   This framework support 2D vector and image-based rendering ad it is a native drawing engine for iOS.
3. Core Animation-
   This framework helps in optimizing the animation experience of the apps in iOS.
4. Media Player Framework-
   This framework provides support for playing the playlist and enables the user to use their iTunes library.
5. AV Kit-
   This framework provides various easy-to-use interfaces for video presentation, recording, and playback of audio and video.
6. Open AL-
   This framework is an Industry Standard Technology for providing Audio.
7. Core Images-
   This framework provides advanced support for motionless images.
8. GL Kit-
   This framework manages advanced 2D and 3D rendering by hardware-accelerated interfaces.

COCOA TOUCH:
COCOA Touch is also known as the application layer, which serves as a user interface for the iOS operating system. It supports touch and motion events, among other things. The following frameworks are provided by the COCOA TOUCH layer:

1. EvenKit Framework-
   This framework shows a standard system interface using view controllers for viewing and changing events.
2. GameKit Framework-
   This framework provides support for users to share their game-related data online using a Game Center.
3. MapKit Framework-
   This framework gives a scrollable map that one can include in your user interface of the app.
4. PushKit Framework-
   This framework provides registration support.