NSTokenField and deleting tokens

Question

My app allows users to attach tags to certain model objects (subclasses of NSManagedObject). The Tag class is also a subclass of NSManagedObject. I decided to use NSTo

Answer 1

You should be able to simulate a delete delegate by creating a token wrapper class that has a pointer back to the owner as well as the wrapped object:

@protocol TokenWrapperDelegate 
-(void)tokenWasDeleted:(id)token;
@end

@interface TokenWrapper : NSObject {
  id owner;
  id token;
}
-(id)initWithWrappedToken:(id)token owner:(id)owner;
@property (nonatomic, weak) id owner;
@property (nonatomic, strong) id token;
@end

Then have the TokenWrapper dealloc notify the owner that the token was deleted:

@implementation TokenWrapper

...

-(void)dealloc {
  [owner tokenWasDeleted:self.token];
  self.token = nil;
  [super dealloc];
}

@end

Then in your representedObjectForEditingString callback, return an autoreleased wrapper pointing at your owner and your real token. You'll also have to make sure to change the other NSTokenField delegate callbacks to delve into the wrapper object. Make sure the owner sets a bit to ignore these callbacks when you're manually changing the contents of the NSTokenField (like by calling setObjectValue).