nsmutableset

Newbie Questions, I have 3 Class, 3 of them are subclass from NSOBject. Collection Class , have 2 properties, masterSong as NSMutableSet (strong, nonatomic) and listOfPlaylists as NSMutableArray (strong, nonatomic) Playlist Class Have 2 properties, playListName as NSString (copy, nonatomic) and songList as NSMutableArray (strong, nonatomic) 3 . Song Class Have 4 properties: title,artist,album, playtime as NSString (copy, nonatomic). masterSong will contain Song object, and listOfPlaylist will contain Playlist Object. while songList only store reference to Song Object. I want to create

In a plain class I have a NSMutableSet property. Whenever objects are added to or removed from the set, I want to perform some custom code. I know I could write a few addObjectToSet: -like methods to the class, but I was wondering if there's a more elegant solution with direct KVO on the set. As it turns out, NSSet will raise an exception when you try to add an observer to it. Not surprisingly, for there's probably no named keyPath to observe. The documentation is pretty clear about the exception, but I don't understand the suggested workaround: Instead of observing a set, observe the

I have two arrays . Array1 contains 15 objects and Array2 contains 4 objects. There are 2 common objects from both array, I just want to get that resulted array of that 2 objects. It should be like intersection of two Set, but how to do in Objective C for array..? Please help. thanks. Using NSMutableSet NSMutableSet *set1 = [NSMutableSet setWithArray: array1]; NSSet *set2 = [NSSet setWithArray: array2]; [set1 intersectSet: set2]; NSArray *resultArray = [set1 allObjects]; 来源： https://stackoverflow.com/questions/12173903/how-to-intersect-two-arrays-in-objective-c

In my app I have a class Person with personId property. Now I need some data structure to hold a bunch of unique Person objects (unique = different personId) So I guess I should use NSMutableSet as my data structure, but how do I make the NSMutableSet compare the personId property when adding a person (so I won't add the same person more then ones)? My goal is to have a collection of unique persons all the time (even if I add two persons with the same id), I want that the NSMutableSet will do all the hard work for me and if I'm adding a person that already exists it won't add it twice. You can