iOS Architecture and its Layers

                                  iOS is derived from MacOS X,which it shares the Darwin foundation, and is a Unix operating system.
  
 iOS consist of four Abstract layers are 

• Cocoa Touch

• Media

• Core Services

• Core OS 

  
  

  Core OS

                    Core OS consist of  C API based on unix, not a object oriented. Core OS handles the following functionalities are OSX kerner,Mach 3.0, BSD, Sockets, Security,Power Management, KeyChain Access, Certificates, File System, Bonjour.

 Core Services 

                                   Core Services classes are Object Oriented.Core Services handles the following functionalities are Collections,Core Location, Address Book, Net Services, Networking, Threading, File Access, Preferences, SQLite, URL Utilities.

 Media

                    Media handles the following functionalities are Core Audio, OpenAL, Audio Mixing, Audio Recording, Video Playback, JPEG,PNG,TIFF, PDF, Quartz(2D), Core Animation, OpenGL ES.

   Cocoa Touch

                                      Cocoa Touch handles the following functionalities are Multie Picker-Touch, Core Motion, View Hierarchy, Localization, Alerts, WebView, Map Kit, Image Picker, Camera, Controls.