Core Data - GROUP BY

I am trying to group results returned by Core Data. I read that you need to use "SortDescriptors" with a selector but I cant seem to get it to work?

I am trying to return group'ed "unique" name values?

http://developer.apple.com/library开发者_StackOverflow社区/ios/#documentation/cocoa/Conceptual/SortDescriptors/Concepts/Creating.html

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Actually, I think you want @distinctUnionOfObjects. See the Xcode Documentation: Key-Value Coding Programming Guide: Collection Operators.

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try using @distinctUnionOfArrays.contactNumber to get the objects