1 ocoa Touch Layer{
App Extensions
https://developer.apple.com/library/ios/documentation/General/Conceptual/ExtensibilityPG/index.html
Handoff
https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/Handoff/HandoffFundamentals/HandoffFundamentals.html
Document Picker
https://developer.apple.com/library/ios/documentation/FileManagement/Conceptual/DocumentPickerProgrammingGuide/Introduction/Introduction.html
AirDrop
https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIActivityViewController_Class/index.html
TextKit
https://developer.apple.com/library/ios/documentation/StringsTextFonts/Conceptual/TextAndWebiPhoneOS/Introduction/Introduction.html
UIKit Dynamics
https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIKit_Framework/index.html
Multitasking
https://developer.apple.com/library/ios/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/Introduction/Introduction.html
Auto Layout
https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/AutolayoutPG/index.html
Storyboards
https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIStoryboard_Class/index.html

UI state Preservation
Apple Push Notification Service/Local Notifications
https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/Chapters/Introduction.html
Gesture Recognizers
https://developer.apple.com/library/ios/documentation/EventHandling/Conceptual/EventHandlingiPhoneOS/Introduction/Introduction.html
Standard System View Controllers
https://developer.apple.com/library/ios/featuredarticles/ViewControllerPGforiPhoneOS/index.html
https://developer.apple.com/library/ios/documentation/WindowsViews/Conceptual/ViewControllerCatalog/Introduction.html

Cocoa Touch Frameworks{
EventKit UI Framework
GameKit Framework
Notification Center Framework https://developer.apple.com/library/ios/documentation/NotificationCenter/Reference/NotificationCenter_Framework/index.html
UIKit Framework
https://developer.apple.com/library/ios/documentation/WindowsViews/Conceptual/ViewPG_iPhoneOS/Introduction/Introduction.html
https://developer.apple.com/library/ios/documentation/Miscellaneous/Conceptual/iPhoneOSTechOverview/iPhoneOSTechnologies/iPhoneOSTechnologies.html
https://developer.apple.com/library/ios/documentation/2DDrawing/Conceptual/DrawingPrintingiOS/Introduction/Introduction.html
https://developer.apple.com/library/ios/documentation/Miscellaneous/Conceptual/iPhoneOSTechOverview/iPhoneOSTechnologies/iPhoneOSTechnologies.html
}
}
2 Media Layer{
Graphics Technologies{
UIKit grahics/Core Graphics framework
https://developer.apple.com/library/ios/documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/Introduction/Introduction.html
https://developer.apple.com/library/ios/documentation/CoreGraphics/Reference/CoreGraphics_Framework/index.html
Core Animation :Core Animation (part of the Quartz Core framework) is a foundational technology UIKit views use Core Animation to provide view-level animation support
https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/CoreAnimation_guide/Introduction/Introduction.html
/Core Image/OpenGL ES and GLKit/Metal/TextKit and CoreText/ImageIO/PhotoLibrary
https://developer.apple.com/library/ios/documentation/GraphicsImaging/Reference/CoreImagingRef/index.html
https://developer.apple.com/library/ios/documentation/StringsTextFonts/Conceptual/CoreText_Programming/Introduction/Introduction.html
https://developer.apple.com/library/ios/documentation/GLkit/Reference/GLKit_Collection/index.html
https://developer.apple.com/library/ios/documentation/GraphicsImaging/Reference/ImageIORefCollection/index.html
}
Audio Technologies{
Media Player framework
https://developer.apple.com/library/ios/documentation/Miscellaneous/Conceptual/iPhoneOSTechOverview/MediaLayer/MediaLayer.html
AV Foundation
OpenAL
Core Audio
}
Video Technologies{
UIImagePickerController
AVKit
AV Foundation
Core Media
https://developer.apple.com/library/ios/documentation/Miscellaneous/Conceptual/iPhoneOSTechOverview/CoreServicesLayer/CoreServicesLayer.html
SpriteKit Framework
https://developer.apple.com/library/ios/documentation/GraphicsAnimation/Conceptual/SpriteKit_PG/Introduction/Introduction.html
}
}
3 Core Services Layer{
https://developer.apple.com/library/ios/featuredarticles/Short_Practical_Guide_Blocks/index.html
https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/Blocks/Articles/00_Introduction.html
https://developer.apple.com/library/ios/documentation/General/Conceptual/ConcurrencyProgrammingGuide/Introduction/Introduction.html
https://developer.apple.com/library/ios/documentation/Performance/Reference/GCD_libdispatch_Ref/index.html
CFNetwork Framework
https://developer.apple.com/library/ios/documentation/Networking/Conceptual/CFNetwork/Introduction/Introduction.html
Foundation.framework provides Objective-C wrappers to many of the features found in the Core Foundation framework

}
4 Core OS Layer{
Accelerate.framework
CoreBluetooth.framework
ExternalAccessory.framework
Generic Security Services Framework GSS.framework
LocalAuthentication.framework
NetworkExtension.framework
Security.framework
system
https://developer.apple.com/library/ios/documentation/System/Conceptual/ManPages_iPhoneOS/index.html
64-bit support
https://developer.apple.com/library/ios/documentation/General/Conceptual/CocoaTouch64BitGuide/Introduction/Introduction.html
}