What's the difference between using a delegate and notification?

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Both are used for sending values and messages to interested parties. A delegate is for one-to-one communication and is a pattern promoted by Apple. In delegation the class raising events will have a property for the delegate and will typically expect it to implement some protocol. The delegating class can then call the _delegate_s protocol methods.
Notification allows a class to broadcast events across the entire application to any interested parties. The broadcasting class doesn't need to know anything about the listeners for this event, therefore notification is very useful in helping to decouple components in an application.
[NSNotificationCenter defaultCenter] 
        postNotificationName:@"TestNotification" 
        object:self];

Comments

  1. Florian24 March 2019 at 14:31

    Great article! I think it's also worth mentioning notifications and KVOs since they are better choices than delegates & blocks in some cases. Here's an interesting article on comparing all 4 swift communication patterns.

    ReplyDelete

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