On Feb 7, 2011, at 8:56 AM, Michael Crawford wrote: > I'm trying to implement a feature where I sort a cross-section of music from > multiple genres with up to two different keys, where the items with a genre > matching the first key appear first in the collection and items with a genre > matching the second key appear after the first group in the collection. All > songs with a genre not matching the first or second keys can be in any order > following the first two groups. > > So I took a look at NSSortDescriptor but it is not apparent to me how I would > accomplish my goal with this class. If I sort with it based on the genre > key, will basically sort them in alphabetical ascending or descending order, > not what I want.
Here are two possible approaches: 1) Implement a synthetic property which is more amenable to the sort ordering you want. Something which returns 0 for the first genre, 1 for the second, and 2 for all others, for example. 2) Implement a custom comparator method that compares the existing genre property in the manner you want: the first genre equal to itself but coming before all others; the second genre coming after the first, equal to itself, and coming before the remaining genres; all other genres coming after the first two but unordered with respect to each other. Either or both of these methods could be implemented in a category if that makes things easier. Regards, Ken _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
