This write-up details the architecture of the Apple Mobile OS: iOS, which helps you do security analysis further; iOS is a Unix powered operating system, so the file system hierarchy is similar to Unix. If you are familiar with the Any *nix system, you can grab the hierarchy quickly. If, in this case, is, you have not explored the File system hierarchy, here you go and have read the same
Additional notes on the file system hierarchy will give another context.
/usr: This directory also contains the include/ subdirectory, where all the standard C headers are.
/etc: The slash etc has a symbolic link to /private/etc in iOS
/tmp: The slash tmp has a symbolic link to /private/tmp.
/var: The slash tmp has a symbolic link to /private/var.
What is slash in the Unix file system?
What is the symbolic link?
iOS Architecture consists of four distinct layers Cocoa Touch, Media, Core Service and Core OS; The hierarchy describes in the below image for the iOS.
Cocoa Touch is the top layer of the iOS architecture. It contains the key Framework UI Kit and defines the basic application infrastructure.
The Cocoa provides the core functionalities like multitasking and touch-based inputs, it includes frameworks such as EvenKit framework, GameKit framework, MapKit framework, MessageKit framework.
EventKit shows the standard system interfaces using view controllers for viewing and changing calendar related events, The GameKit provides support for users to share their game related data online using Game centre, and The MapKit provides a scrollable map which can be included into the app user interface.
The media layer provides iOS with all the functionalities to support audio, video, animation, and graphics. It retains frameworks such as the Core Audio framework, Core Text framework, and Core Image framework.
UIKit Graphics provides support for designing images and animating the view content.
Core Graphics Framework provides support for 2-D vector and image-based rendering and is the native drawing engine for iOS apps.
Core Animation technology optimizes the animation experience of the apps.
Media Player Framework provides support for playing playlists and enables the user to use their iTunes library.
AV Kit provides various easy to use interfaces for video presentation.
Core Service Layer provides services used in upper layers, and It holds frameworks such as Address Book framework, Core Location framework, Core Telephony framework.
Cloudkit Framework uses to move the data between the app the iCloud using the Cloudkit Framework.
Core Foundation Framework delivers the data management and service features for the iOS apps.
Core Data Framework handle the data model of the model view controller app.
Address Book Framework provides access to the contact database of the user.
Core Motion Framework uses to access all the motion-based data
Healthkit Framework bears the health related information.
Core Location Framework delivers the location and heading information to the various apps.
Core OS Layer is the iOS technology built on the low-level features provided by the Core OS layer. And it includes processing, interfacing and security support for the iOS application, Accelerate framework, System framework, Core Bluetooth Framework, Local Authorisation Framework, External Accessory and Security framework.
The overview of the iOS with the following service is listed below.
Kernel and Device Drivers The lowest layer of OS X includes the kernel, drivers, and BSD portions of the system and is based primarily on open-source technologies. OS X extends this low-level environment with several core infrastructure technologies that make it easier for you to develop software.
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PS: The write-up is learning notes, so please clap if this is helped you understand the iOS architecture and iOS file system in any way.
Reference :
https://www.tutorialspoint.com/apple-ios-architecture
