How Do I sort an NSMutable Array with NSNumbers in it?

Question

I'm trying to make a high score table, and suck at arrays in objective c (actually, in general objective c is challenging for me), so I can't figure out how to sort. I'm trying to do something like this (speudocode, I'm writing this in actionscript style because I'm more comfortable with it):

highscores.addObjecttoArray(score)
highscores.sort(ascending)

But I can't figure it out... I've seen other threads about it, but their use plist files and stuff and I don't know enough objective c to learn from them.

Answer 1

[highscores sortUsingSelector:@selector(compare:)];

Should work if they're definitely all NSNumbers.

(Adding an object is:

[highscores addObject:score];

)

If you want to sort descending (highest-first):

10.6/iOS 4:

[highscores sortUsingComparator:^(id obj1, id obj2) {
    if (obj1 > obj2)
        return NSOrderedAscending;
    else if (obj1 < obj2)
        return NSOrderedDescending;

    return NSOrderedSame;
}];

Otherwise you can define a category method, e.g.:

@interface NSNumber (CustomSorting)

- (NSComparisonResult)reverseCompare:(NSNumber *)otherNumber;

@end

@implementation NSMutableArray (CustomSorting)

- (NSComparisonResult)reverseCompare:(NSNumber *)otherNumber {
    return [otherNumber compare:self];
}

@end

And call it:

[highscores sortUsingSelector:@selector(reverseCompare:)];

Answer 2

Would you like to do that the short way?

If you have a mutable array of NSNumber instances:

NSSortDescriptor *highestToLowest = [NSSortDescriptor sortDescriptorWithKey:@"self" ascending:NO];
[mutableArrayOfNumbers sortUsingDescriptors:[NSArray arrayWithObject:highestToLowest]];

Nice and easy :)

You can also perform similar sorting with descriptors on immutable arrays, but you will end up with a copy, instead of in-place sorting.