All you need to know about the Architecture of iOS

Nov 10, 2022

iOS is fully distinct from other operating systems as it is designed to retain all of the devices within its safe shell. iOS micromanages mechanisms and automation sequentially in layers inside the operating system. Individual layers encompass multiple programming frameworks to be utilized and implemented through the application areas.

The architecture has four layers, and communication is enhanced by a layer that joins the application and hardware layers. A low-level layer postulates the services that all applications are in need of, although an upper-level layer or high-level layer provides graphics and interface-related services.

The system interfaces come with a special package known as the Framework. A framework is a gradable directory that encapsulates shared resources, mainly dynamic shared libraries like .a files, header files, images, and helper apps that support the library. Each layer has a set of frameworks that are favorable for iOS developers.

  1. Core OS Layer: It is the bottom level of the hierarchical structure. All the iOS technologies are bred-in-the-bone in the lowest level layer, i.e., the Core OS layer. This layer explicitly resides on the top of the device hardware and is the bottom layer of the iPhone OS stack. It is inclusive of the basic operating system services, namely memory management until the program is complete, handling of file systems, and threads. This layer comes up with low-tier networking, an approach to external accessories, etc.

This technology incorporates:

  • The Core Bluetooth Framework interacts with classic and low-energy Bluetooth. It handles low-level connection parameters and transfers data between BLE devices.
  • The External Accessories Framework provides a conduit for communicating with accessories of devices that are connected via Bluetooth or the Apple Lightning connector.
  • The Accelerate Framework performs large-scale mathematical computations on the CPU and image calculations optimized for high performance and low energy consumption.
  • The Security Services Framework controls access to the app and the data privacy it maintains.
  • The Local Authorization Framework authenticates users by using biometrics or passphrases that they are familiar with.

The main OS layer includes a range of frameworks that can be plainly used, such as the Accelerate and Protection frameworks. For apparent security, the Core OS also embodies the kernel framework and low-grade UNIX interface, through which an app has no exposure.

2. The Core Services Layer is the 2nd lowest layer in the architecture of iOS and steers the primary device services that are used by native iOS users. Efforts are to customize the services required by the higher tiers of users. Important features of the alternative are block items, Grand Central Dispatch, in-app purchases, and iCloud storage. The service layer has been enhanced with the inclusion of ARC. ARC (Automatic Reference Counting) is an important complement to our core services. ARC is a pre-processor level service network that optimizes Objective-C memory management.

The Core Services layer contains several key frameworks that help iOS work intrinsically and provide better functionality.

The framework is shown below-

  • The Address Book Framework: The Address Book Framework defines how to interact with the device's address book database. You can get all the entities in your user book and add and change their values.
  • Cloud Kit Framework: This is designed for manageability, flexibility, and performance. CloudKit keeps each app separate without tangling with data. With efficient sync and share capabilities, CloudKit offers a comprehensive feature set that makes it easy to develop powerful cloud apps.
  • Core Data Framework: The schema of CloudKit containers is automatically mirrored by Core Data. Core Data abstracts away the details of how objects are associated with transactions, making it easy to store data from Swift without managing a database directly.
  • Core Foundation Framework: This framework enables basic data management, application environment, and service functionality for iOS applications.
  • Core Location Framework: This framework supports the management of geolocation, altitude, orientation, and orientation information for applications. This framework collects all data via Wi-Fi, GPS, Bluetooth, and cellular hardware.
  • Core Motion Framework: All the motion and environmental-related data on the device is retrieved as a consequence of the core motion framework. Several services access both the raw values recorded by hardware and a processed version of those values.
  • Foundation Framework: This is the salt and pepper of an iOS developer's toolbox. This dispenses with the root class building blocks for iOS development.
  • HealthKit Framework: Apple introduced the HealthKit Framework when it introduced iOS 8. It serves as a central repository for all health-related data. This oversees the health-related information of the user.
  • HomeKit Framework: This framework is for controlling home automation. This is meant for talking with and controlling connected devices in the user’s home.
  • Social Framework: It is solely an alliance that will access a user’s social media accounts.
  • StoreKit Framework: This framework provides and supports a simple and secure way to purchase content and services across all iOS apps.

3. The Media Layer: The media layer allows the image on an iOS device to be clear and the music to be transparent. All the media, mainly graphics, video, and audio, are included in this layer which helps in furnishing an immersive experience for the mobile. There is a wide range of primary innovations in this layer, such as Open GL, Core graphics, AV foundation, Open AL, etc. The media layer inculcates a huge number of frames, such as the Assets Libraries system for accessing the images and videos stored on the device. The graphics in the UL Kit advocate for enticing and animating the subject. The Open AL framework is an industry-standard technology that is approachable for dispensing audio. The GL Kit oversees advanced 2D and 3D rendering through hardware-accelerated frameworks. The AV Kit provides an uncomplicated juncture for the presentation of video and audio recordings. Core graphics supports 2D vector and image-based rendering ads.

4. The Cocoa Layer: It is the topmost layer and also known as the Application Layer, which acts as a terminal for the user to work with iOS. It supports touch and motion events. The Cocoa Touch layer contains a range of high-level iOS framework features, such as the opportunity to multi-task among apps or touchscreen use to execute commands. The event framework provides access to calendar and reminder data so that users can retrieve, create, and edit calendar items in the app. The GameKit framework enables the user to share all their game-related data online via a game center. The MapKit framework provides a map that can be included in the interface of the application. The UIKit framework is customized for the iOS platform, which offers a visual, event-guided iOS framework.

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