Delegates: Difference between revisions

<lang objc>#import <Cocoa/Cocoa.h>

 

id delegate;

}

- (id)delegate;

- (void)setDelegate:(id)obj;

- (NSString *)operation;

@end

 

@implementation Delegator

return delegate;

}

delegate = obj; // Weak reference

}

if ([delegate respondsToSelector:@selector(thing)])

return [delegate thing];

return @"default implementation";

}

@end

 

// Any object may implement these

@interface NSObject (DelegatorDelegating)

- (NSString *)thing;

@end

 

@interface Delegate : NSObject

// Don't need to declare -thing because any NSObject has this method

@end

 

@implementation Delegate

return @"delegate implementation";

}

@end

 

// Example usage

// Memory management ignored for simplification

// Without a delegate:

Delegator *a = [[Delegator alloc] init];