world’s most advanced mobile OS.
iOS (originally iPhone OS) is a mobile operating system
created by Apple company. It is the second most popular mobile operating system
in the world after Android. Apple's App Store contains more than 1.4 million
iOS applications, 725,000 of which are for iPads. The current release, iOS 9.2,
was released on December 8, 2015.
iOS Architecture:
In the structure of iPhone we looked at the hardware. When
we develop apps for the iPhone, Apple does not allow us direct access to any of
this hardware. In fact, all hardware communication takes place through a number
of different layers of software that act as completely between the applications
and device hardware. These layers made a system that we called operating
system. In the world of iPhone, this operating system is known as the iPhone
OS.
An Overview of the iPhone OS Architecture:
As discussed above, the iPhone OS consists of a number of
different software layers, each provides programming frameworks for the
development of applications that run on top of the operating system.
These layers are as follows:
1- The iPhone OS Cocoa Touch Layer
2- The iPhone OS Media Layer
3- The iPhone OS Core Services Layer
4- The iPhone OS Core OS Layer
The iPhone OS Cocoa
Touch Layer
The Cocoa Touch layer contains the frameworks that are most
commonly used by iPhone application developers. Cocoa Touch is basically
written in Objective-C, is based on the standard Mac OS X Cocoa API and has
been extended and modified to meet the needs of the iPhone.
The iPhone OS Media
Layer
The role of the Media layer is to provide the iPhone OS with
audio, video, animation and graphics facilities. As with the other layers cover
the iPhone OS stack, the Media layer contains a number of frameworks that can
be utilized when developing iPhone apps.
The iPhone OS Core
Services Layer
The iPhone Core Services layer provides much of the base on
which the above layers are built.
The iPhone OS Core OS
Layer
The Core OS Layer is the bottom layer of the iPhone OS
stack. This layer provides a variety of services including low level
networking, access to external accessories and the usual fundamental operating
system services such as memory management, file system handling and threads.
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