How to sort an NSArray of objects by their class?

Question

I have an NSArray of objects that all subclass with their different types from a more abstract class.

I would like to sort the array by the object's class type. For example:

NSArray with CLASSA CLASSB AND CLASS C subclassed from CLASSz

myArray = {C, B, A}

Sort myArray decending: {A, B, C}

I see sort descriptors and that seems like it's the right path but I am comparing isKindOfClass which is not a property so can not be used in the NSSortDescriptiors thing.

Thanks for any help.

Answer 1

Well, the biggest hurdle I see is that you're probably going to need a custom property on Class objects which you could use as the key of an NSSortDescriptor. Unfortunately, there's no real way to add methods/categories to Class objects.

So what I would probably do is use NSStringFromClass() to convert your Class objects into strings, then use an NSString category to add a custom comparator method (something like compareToClass:) that converts the string back to a Class, does the subclass determination, and then returns the appropriate ordering constant.

From there, you can use NSArray's sortedArrayUsingSelector: method to get them in order.