macOS NSArray NSTreeController subset....

[BollywooD]

Im stumped.
I have an NSTreeController, which is a subset of an NSArray. Contained in both is are objects which are flagged as favorites, or non favorites. I want to save only differences between the two, into a new NSArray.

for example:

NSArray has the following objects:
apple (favorite)
orange
carrot
banana
pear (favorite)

NSTreeController
apple
orange (favorite)


I would like to have a new combined NSArray, with the following objects:
apple
orange (favorite)
carrot
banana
pear (favorite)


how would I go about doing this?

thanks in advance

 

[BollywooD]

I just discovered NSSet does exactly I need, as it only stores unique objects.