Sorting array(NSArray) in descending order

Question

I have a array of NSString objects which I have to sort by descending.

Since I did not find any API to sort the array in descending order I approached by following way.

I wrote a category for NSString as listed bellow.

- (NSComparisonResult)CompareDescending:(NSString *)aString
{

    NSComparisonResult returnResult = NSOrderedSame;

    returnResult = [self compare:aString];

    if(NSOrderedAscending == returnResult)
        returnResult = NSOrderedDescending;
    else if(NSOrderedDescending == returnResult)
        returnResult = NSOrderedAscending;

    return returnResult;
}

Then I sorted the array using the statement

NSArray *sortedArray = [inFileTypes sortedArrayUsingSelector:@selector(CompareDescending:)];

Is this right solution? is there a better solution?

dgatwood · Accepted Answer · 2018-02-15 19:15:22Z

56

You can use NSSortDescriptor:

NSSortDescriptor* sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:nil ascending:NO selector:@selector(localizedCompare:)];
NSArray* sortedArray = [inFileTypes sortedArrayUsingDescriptors:@[sortDescriptor]];

Here we use localizedCompare: to compare the strings, and pass NO to the ascending: option to sort in descending order.

edited Feb 15, 2018 at 19:15

dgatwood

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answered Dec 21, 2009 at 9:04

Ciarán Walsh

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2 Comments

Girish Kolari Over a year ago

since 'sortDescriptorWithKey' 10.6 aboveI have used following statement. [[NSSortDescriptor alloc] initWithKey: nil ascending: NO]; thanks...

Ciarán Walsh Over a year ago

Indeed, I should have mentioned that – don’t forget the -autorelease though :)

Jiri Zachar · Accepted Answer · 2015-08-11 12:50:31Z

10

or simplify your solution:

NSArray *temp = [[NSArray alloc] initWithObjects:@"b", @"c", @"5", @"d", @"85", nil];
NSArray *sortedArray = [temp  sortedArrayUsingComparator:
                        ^NSComparisonResult(id obj1, id obj2){
                            //descending order
                            return [obj2 compare:obj1]; 
                            //ascending order
                            return [obj1 compare:obj2];
                        }];
NSLog(@"%@", sortedArray);

answered Aug 11, 2015 at 12:50

Jiri Zachar

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Comments

ankit yadav · Accepted Answer · 2012-11-21 08:10:19Z

6

NSSortDescriptor *sortDescriptor; 
sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"length" ascending:NO];
NSArray *sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
[wordsArray sortUsingDescriptors:sortDescriptors];

Using this code we can sort the array in descending order on the basis of length.

edited Nov 21, 2012 at 8:10

answered Nov 21, 2012 at 7:57

ankit yadav

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