What is the difference between Delegate and Notification?

Question

What is the difference between Delegate and Notification?

I understood like delegate and protocol,

@protocol classADelegate

-(void)DelegateMethod;

         


        

Answer 1

Simply We can say,

Delegates:

One - to - One

Notification:

One - to - Many

To declare Delegate

@protocol DelegateName
@required
- (void)method:(NSString *)param;
@optional
- (void)methodOptional:(NSString *)param;
@end

And declare a property for Protocol

@property id  delegate;

You can use

myObject.delegate = <# some object conforming to DelegateName #>;

NSNotification declaration

[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(notificationHappened:)
                                             name:MyCustomNotificationName
                                           object:nil];

Then Implement

- (void)notificationHappened:(NSNotification *)notification {
    // do work here
}

You can post Notification from anywhere using,

[[NSNotificationCenter defaultCenter] postNotificationName:MyCustomNotificationName
                                                    object:self
                                                  userInfo:nil];

call removeObserver: when you are finished.