How to sort NSArray of custom objects by a specific property in descending order?

Question

How do I make this piece of code to order in descending order. This code always gives me the array in ascending order:

NSArray *sortedProductsByStyle = [unsortedProducts sortedArrayUsingComparator: ^(Product *p1, Product *p2) {
        return [p1.productStyle compare:p2.productStyle options:NSNumericSearch];
    }];

I thought that using NSOrderedDescending would work but it didn't:

NSArray *sortedProductsByStyle = [unsortedProducts sortedArrayUsingComparator: ^(Product *p1, Product *p2) {
        return [p1.productStyle compare:p2.productStyle options:NSNumericSearch | NSOrderedDescending];
    }];

Any ideas?

what is a type of "productStyle" ?

Andrey Gordeev
– Andrey Gordeev

2013-10-07 04:30:52 +00:00
Commented Oct 7, 2013 at 4:30 — Andrey Gordeev
– Andrey Gordeev, Commented Oct 7, 2013 at 4:30
It is of type NSString but only holds number data

Renexandro
– Renexandro

2013-10-08 19:37:01 +00:00
Commented Oct 8, 2013 at 19:37 — Renexandro
– Renexandro, Commented Oct 8, 2013 at 19:37

Gabriele Petronella · Accepted Answer · 2013-10-07 04:36:27Z

5

How about just inverting the compare order?

NSArray *sortedProductsByStyle = [unsortedProducts sortedArrayUsingComparator: ^(Product *p1, Product *p2) {
    return [p2.productStyle compare:p1.productStyle options:NSNumericSearch];
}];

answered Oct 7, 2013 at 4:36

Gabriele Petronella

108k21 gold badges223 silver badges238 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Renexandro Over a year ago

I tested it, and in this particular escenario it actually works. Let's see what happens when is not a numeric search, i think is going to work too, though. Thank you very much Gabriele!

Gabriele Petronella Over a year ago

NSNumericSearch changes the result of the compare, according to the type (which you didn't specify in your question). That said, inverting the comparison order will always invert the final result order ;)

user1673099 · Accepted Answer · 2013-10-07 04:38:54Z

-1

Try this way...

sortedArray = [unsortedProducts sortedArrayUsingComparator:^(Product p1 , Product p2) {
            return [((NSString *)p1.productStyle) compare:((NSString *)p2.productStyle) options:NSNumericSearch];
        }];

Let me know if you have any problem.

edited Oct 7, 2013 at 4:38

answered Oct 7, 2013 at 4:33

user1673099

3,2997 gold badges30 silver badges57 bronze badges

7 Comments

Gabriele Petronella Over a year ago

Why should the cast help?

Gabriele Petronella Over a year ago

I think you are confused about what casting does.

Gabriele Petronella Over a year ago

1. if productStyle is an integer, the original code won't even compile. 2. Casting does not change the type of the object, it just makes the compiler believe it is a NSString, but at runtime it changes nothing.

user1673099 Over a year ago

@GabrielePetronella, i know it just consider as a string.

Gabriele Petronella Over a year ago

Adding a cast, as you propose, changes nothing if productStyle is a NSString and it's just wrong and potentially dangerous if it's not.

|

Collectives™ on Stack Overflow

How to sort NSArray of custom objects by a specific property in descending order?

2 Answers 2

2 Comments

7 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

7 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related