The
NSSet, NSMutableSet, and NSCountedSet classes declare the programmatic interface to an unordered collection of objects.NSSet declares the programmatic interface for static sets of distinct objects. You establish a static set’s entries when it’s created, and thereafter the entries can’t be modified. NSMutableSet, on the other hand, declares a programmatic interface for dynamic sets of distinct objects. A dynamic—or mutable—set allows the addition and deletion of entries at any time, automatically allocating memory as needed.You can use sets as an alternative to arrays when the order of elements isn’t important and performance in testing whether an object is contained in the set is a consideration—while arrays are ordered, testing for membership is slower than with sets.
This may not be directly applicable but it is a solution to creating a unique set of values... Assume you have a NSMutable array of events that have multiple duplicate entries. This array is named eventArray. The NSSet object can be used to trim that array and then repopulate that array as shown below... NSSet *uniqueEvents = [NSSet setWithArray:eventArray]; [eventArray removeAllObjects]; [eventArray addObjectsFromArray:[uniqueEvents allObjects]]; |
