SBJson framework is supported by iOS. It is a JSON parser and generator for Objective-C. SBJson provides flexible APIs and additional control that makes JSON handling easier.

The Singleton design pattern ensures a class only has one instance, and provides a global point of access to it. The class keeps track of its sole instance and ensures that no other instance can be created. Singleton classes are appropriate for situations where it makes sense for a single object to provide access to a global resource.Several Cocoa framework classes are singletons. They includeNSFileManager, NSWorkspace, NSApplication, and, in UIKit,UIApplication. A process is limited to one instance of these classes. When a client asks the class for an instance, it gets a shared instance, which is lazily created upon the first request.

The app delegate object is created by UIApplicationMain function at app launch time. The app delegate object's main job is to handle state transitions within the app.

During app launching, the system creates a main thread for the app and calls the app’s main function on that main thread. The Xcode project's default main function hands over control to the UIKit framework, which takes care of initializing the app before it is run.

Cocoa is for Mac App development  and cocoa touch is for apples touch devices - that provide all development environment 

A scheduling agreement can be made for Consignment, Subcontracting and stock transfer. A contract, also known as a blanket PO, can be made for standard items and can be restricted to a Value or QTY.

LSMW is widely used by EDI programmers. EDI Programmers connect the SAP system to Non SAP system. During this Data migration is a necessity. When data migrates from source to destination the destination code is differrent from the source code. So what LSMW does is 

* Converts the data in to batch files

* Then converts the batch files in to source code batch files 

* And then mirgates data. Standard Interfaces like BAPI or Idoc are used in this process.

OOABAP is used to develop BSP/PCUI applications and also anthing involved object oriented like BADIs, SmartForms..etc.where as ABAP is used to develop traditional programs in R/3.