iOS NSNotification

NSNotification is a great and simple way to inform other 

methods to trigger in different classes

eg : we have two classes : class A and class B , in class B 

we perform some tasks and we have to inform class A that 

class B has finished it's task so, we can handle this by

simple implementation of two piece of code : one is post 

notification which has to implement in class B and other one

will be implemented in class A which will receive notification from class 

Class B:

Below method you can implement after completing any task with any

 key liek ("Task_done")

    [[NSNotificationCenter defaultCenter]

     postNotificationName:@"Task_done"

     object:self];

Class A:

This class will receive notification with the same key , and it

 will automatically call the method (AfterTaskDone:)

    [[NSNotificationCenter defaultCenter] addObserver:self

                                             selector:@selector(AfterTaskDone:)

                                                 name:@"Task_done"        object:nil];

-(void)AfterTaskDone{

    

}