1.Define Visibility in Objective C? Answer:- Visibility :
The Objective C has variable by default @protected. But methods are not used with access specifier they are public by default. To hide any method from out side . Declare and Implement it in .m file using category .
NSCoder is an abstractClass which represents a stream of data. They are used in Archiving and Un-archiving objects. NSCoder objects are usually used in a method that is being implemented so that the class conforms to the protocol.