One Quickie

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Making a delegate (NSObject->General)

You've decided you want your class to have a delegate. Here's how you go about doing it:

1. Make an id instance variable in your class, and make methods to set and get it:

   id   delegate;
   ...
   -(void) setDelegate: (id) del
   {
       delegate = del; // you don't need to retain it
   } // setDelegate
   
   - (id) delegate
   {
       return (delegate);
   } // delegate
   

2. Make a category on NSObject so the compiler won't generate warnings, and also to document the delegate methods you support:

   @interface NSObject(BWStitchViewDelegate)
   - (BOOL) shouldHandleStuff: (NSData *) data;
   @end
   

3. Check to make sure your delegate understands the message before sending it.

   ...
   if ([delegate respondsToSelector: @selector(shouldHandleStuff:)]) {
       BOOL blah;
       blah = [delegate shouldHandleStuff: somedata];
       if (blah) ...
   }