iOS is Apples 's mobile operating system
iOS's application structure is hierarchical
It make possible for iOS to communicate directly with the hardware
consist of "Cocoa/Cocoa Touch", "Media","Core Services", "Core OS"
Cocoa/Cocoa Touch
- provide infrastructure for all applications
- mainly responsible for app interface
Media
- Library that display graphics, video and audio
Core Services
- Provides other systems of the systems to the application(network, location)
- Provides essential functions of the apps
Core OS
- Librarys used to run tasks on the rest of the upper layer
Also, iOS has security Model and hierarchical process about that.
Security Model
- Layer security architecture down to hardware, operating system, and application levels (secure boot chain)
- Application sandbox
- Encryption right at the hardware/firmware level
- Data protection through encryption
- code signing
Bootchain & SandBox & Code Signing
Boot chain's process is also hierarchical.
- Boot ROM
- LLM
- iBoot
- iOS Kernel
Whenever boot iOS, each stage must be tested.
sandbox is an iOS control technology that runs in the kernel
- preventing damage to the system and user's data in case of app corruption
- preventing applications from accessing other unrelated data, separating privilieges
Code Signing
- Implementing DRM system so that code signed by Apple runs
- Unsigned apps from the App store cannot be installed
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