Protocols & delegates [duplicate]

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Possible Duplicate:

What is the difference between Notifications, Delegates, and Protocols?

I am new in Objective C. Would like to understand the concept of Protocols and Delegates in a few words. Like under what situation should I consider declaring a Protocol, and then consume it in my classes as delegates or let other classes consume it.

Instea开发者_高级运维d of Protocols why can't I make my classes do the same job?

Thanks for your time.

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Protocols are like contracts, Your class must implement all methods that are @required, @optional are on the other hand not required.

Instead of Protocols why can't I make my classes do the same job? You can, but like I wrote above, its a contract. You know that class

implements the (Required) methods.

delegate is (should be) a weak reference to the class that implements the given protocol.

You are recommended to use the following attribute on your delegateproperty:

@property (assign) id<yourProtocol> delegate;

Notice that you don't retain your delegate. You you (weak) reference because you dont want to get into a retain circle (A retains B, and B retains A).

I hope my explanation helped a bit.