CODEWITHSUNDEEP
objective-cdelegatesprotocols
Paul
Paul

Reputation: 6176

delegate declared in interface/protocol?

could you help me understand something with the delegates and protocols :
in this code : 

          @protocol FirstViewControllerDelegate;  
            @interface FirstViewController : UIVIewController {
            …
            id<FirstViewControllerDelegate> delegate;
            }
            @property (assign) id <FirstViewControllerDelegate> delegate;

Thanks for your answer

Paul

Upvotes: 0

Views: 301

Answers (1)

Paul.s
Paul.s

Reputation: 38728

The 

@protocol FirstViewControllerDelegate;

in that format is a forward declaration. It tells the compiler that FirstViewControllerDelegate is a valid protocol that will be defined later on (sometimes just further down in the same .h file). It is required because without it the compiler will complain when it sees the line 

id<FirstViewControllerDelegate>

as it has not seen its declaration.

The actual protocol may be defined something like

@protocol FirstViewControllerDelegate
{
@required
  - (void)myImportantDelegateMethod;
}

Upvotes: 1

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