ios - What is the best way to get unique set of objects from an array in objective C -

i have array list of model objects

model object has properties name, age, gender, have date follows

user* user1.name = "bob",  user1.age = "10", user1.gender = "m",  user* user2.name = "bob",  user2.age = "11", user2.gender = "m",  user* user3.name = "woz",  user3.age = "15", user3.gender = "m",  user* user4.name = "woz",  user4.age = "16", user4.gender = "m", 

now need unique name , lesser age result.

user* user1.name = "bob",  user1.age = "10", user1.gender = "m",  user* user3.name = "woz",  user3.age = "15", user3.gender = "m", 

what efficient way derive above result. in advance hint or appreciated.

you can iterate array looking youngest users, storing each 1 in dictionary keyed name. once have iterated array of dictionary values array;

-(nsarray*)getyoungestuniqueusersfromarray:(nsarray*)users {      nsmutabledictionary* youngestusersdict = [nsmutabledictionary new];      (user* user in users) {         user* currentuser = youngestusersdict[user.name];         if (currentuser == nil || user.age < currentuser.age) {             youngestusersdict[user.name]=user;         }     }      nsarray* youngestusers = [youngestusersdict allvalues];      return youngestusers; }