Delegates in Objective C

Delegate in Objective C is used when one class objects wants to assign some of its work to another object.
Example:- in NSTableView we want cell to be drawn as per requirement. So we can delegate that adding data to cell will be done by that another delegate class object.


use of category with delegate

@interface NSObject  (NSCommonDelegateMethods)

- (void) commonMethodForallclass: (NSObject *) browser;

@end

 By putting a category on NSObject , any kind of object can be used as a delegate object. There

is no need to inherit from a specialized   class.

Adding  category on NSObject  is called creating an informal protocol.