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

Question

I have an array with list of model objects

model object has properties Name, Age, gender, I have date as 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 I need to get the unique name and lesser age as result.

user* user1.name = "Bob", 
user1.age = "10",
user1.gender = "M",

user* user3.name = "Woz", 
user3.age = "15",
user3.gender = "M",

what would be the efficient way to derive the above result. Thanks In advance Any Hint or help would appreciated.

Answer 1

You can simply iterate the array looking for the youngest users, storing each one in a dictionary keyed by name. Once you have iterated the array simply get all of the dictionary values as an array;

-(NSArray*)getYoungestUniqueUsersFromArray:(NSArray*)users {

    NSMutableDictionary* youngestUsersDict = [NSMutableDictionary new];

    for (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;
}