How to implement a custom protocol

In this part of my code I get开发者_高级运维 a warning message saying it doesn't implement the custom protocol I made.

detailViewController.delegate = self;

How do I implement the protocol?

Then when I run the program it crashes saying

'-[DetailViewController setDelegate:]: unrecognized selector sent to instance 0x6a1c450'

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Declare your class like this:

@interface DetailViewController : UIViewController <MyProtocol> {
    // Class stuff
}