Sorting NSMutableSet

Question

I have to use NSMutableSet to store my string objects. I wan to store them in right order for example from smallest to biggest number:

1
2
3
4

How ever if do this:

NSMutableSet *set = [[NSMutableSet alloc] init];
[set addObject:[NSString stringWithFormat:@"1"]];
[set addObject:[NSString stringWithFormat:@"2"]];
[set addObject:[NSString stringWithFormat:@"3"]];
[set addObject:[NSString stringWithFormat:@"4"]];
NSLog(@"set is %@",set);
[set release];

I don't get what i wanted but instead this:

set is {(
    3,
    1,
    4,
    2
)}

So I guess i need to sort them to get wanted result ? But really i can't find any example.

Maybe someone could help me on this ?

Thanks.

EDIT: I can't use else. Just NSMutableSet or NSSet

Answer 1

If there's any characteristic of the NSSet is that they dont have any order!

You should use a NSMutableArray for your purpose.

Read about collections here, it will help you

https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/Collections/Collections.html#//apple_ref/doc/uid/10000034-BBCFIHFH

Answer 2

As everybody else has said, NSSet is unsorted by definition. Howeever, if you have to use NSMutableSet you can get a sorted array from the elements using something like (assuming, in this case the elements are strings)

NSArray* unsorted = [mySet allObjects];
NSArray* sorted = [unsorted sortedArrayUsingComparator: ^(NSString* string1, NSString* string2)
                   {
                       return [string1 localizedCompare: string2];
                   }];

Answer 3

An 'NSSet' is unordered. It is meant to contain only unique items (no duplicate items). From Apples docs of NSSet:

...declare the programmatic interface to an unordered collection of objects.

If you want order, go for NSMutableArray or NSMutableOrderedSet.

Answer 4

try this

NSMutableSet *set = [[NSMutableSet alloc] init];
[set addObject:[NSString stringWithFormat:@"1"]];
[set addObject:[NSString stringWithFormat:@"2"]];
[set addObject:[NSString stringWithFormat:@"3"]];
[set addObject:[NSString stringWithFormat:@"4"]];

NSLog(@"%@",set); // Output (3,1,4,2,5) ... all objects

NSSortDescriptor *sort = [NSSortDescriptor sortDescriptorWithKey:@"description" ascending:YES];
NSArray *sortedArray = [set sortedArrayUsingDescriptors:[NSArray arrayWithObject:sort]];

NSLog(@"%@",sortedArray);

Answer 5

NSMutableSet is by definition unordered. Sorry.

https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSMutableSet_Class/Reference/NSMutableSet.html

Answer 6

Sets are unordered by definition. You need an ordered set by using NSMutableOrderedSet or NSOrderedSet which are available in MacOS X 10.7 or later.