ios - Subtract NSSet from other NSSet

I have two NSSets. One contains all UserKeys and other contains online user keys. I want to show in two sections this values. Section 1- online users and section2 - other users

I did this using predicate like below.

NSSet *nsset1 = [NSSet setWithArray:attendeesService.arrof_attendeeList]; //this are all users
nsset2 = [NSSet setWithArray:tempArray]; // temparray contains all online users.
NSSet *nsset2_ids = [nsset2 valueForKey:@"UserProfileKEY"]; 
nsset1_minus_nsset2 = [nsset1 filteredSetUsingPredicate:[NSPredicate predicateWithFormat:@"NOT UserProfileKEY IN %@",nsset2_ids]];

It works fine. But All users are about 3000+ and online may be 200+ at a time. So it is taking a lot of time. It takes 1 min for 4-5 online users. So for 200+ online users will take more time. Is there a faster solution for this?

Thanks.

Solution

Your First Array is FirstMakes declaration is :

NSArray *FirstMakes = @[@"Mercedes-Benz", @"BMW", @"Porsche",
                         @"Opel", @"Volkswagen", @"Audi"];

Your second Array is SecondMakes declaration is :

NSArray *SecondMakes = @[@"Mercedes-Benz", @"Porsche",
                          @"Volkswagen"];

Filter `FirstMakes` to `SecondMakes`

NSPredicate *beforeL = [NSPredicate predicateWithBlock:
                            ^BOOL(id evaluatedObject, NSDictionary *bindings)
                             {

                                 if ([SecondMakes containsObject:evaluatedObject])
                                 {
                                     return NO;
                                 }
                                 else{
                                     return YES;
                                 }

                            }];
    NSArray *makesBeforeL = [FirstMakes
                             filteredArrayUsingPredicate:beforeL];

    NSLog(@"%@", makesBeforeL);

Your OUTPUT is :

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