How to sort NSArray of NSStrings using NSPredicate?

Question

I have NSarray contains the list of Animals. The array contains a list of animals with repeated elements. I have to make an array with distinct values in the array. Repeated values should be removed using NSPredicate.

Here is my Code :-

NSArray *arrAnimals = [[NSArray alloc] initWithObjects:@"Cat",@"Rat",@"Fish",@"Cat",@"Fish",@"Cat",@"Cat",@"Bird",@"Fish",@"Cat",@"Frog", nil];

NSPredicate *predicate = [NSPredicate predicateWithFormat:[NSString stringWithFormat:@"distinct"]];
arrAnimals = [arrAnimals filteredArrayUsingPredicate:predicate];

Here I am using "distinct" keyword for sorting the array, but not able to find any solution. I have preferred many links.

http://www.infragistics.com/community/blogs/stevez/archive/2013/10/21/ios-objective-c-filtering-a-nsarray-using-nspredicate.aspx

Please resolve my problem.

Is your goal to remove duplicates, or sort alphabetically? Or both? — Craig Otis, Jul 07 '14 at 12:07
http://stackoverflow.com/questions/1351182/how-to-sort-a-nsarray-alphabetically — Yogendra, Jul 07 '14 at 12:13
Yaah my goal is to remove duplicate entries and sort alphabetically too. — Apoorv, Jul 07 '14 at 12:22

score 2 · Answer 1 · answered Jul 07 '14 at 12:20

2

There is no predicate for this, but you can use Key-Value Operator:

distinct = [array valueForKeyPath:@"@distinctUnionOfObjects.self"];

answered Jul 07 '14 at 12:20

Tricertops

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Thanks for the keyword "distinctUnionOfObjects.self". This method will also returns sorted array. After removing repeated values. – Apoorv Jul 07 '14 at 12:40
It preserves the order, so if your original array is sorted, the result will be too. – Tricertops Jul 07 '14 at 13:18

score 1 · Answer 2 · answered Jul 07 '14 at 12:07

1

You can remove duplicates from an array by creating a set with its objects and converting it back to an array.

NSArray *arrAnimals = [[NSArray alloc] initWithObjects:@"Cat",@"Rat",@"Fish",@"Cat",@"Fish",@"Cat",@"Cat",@"Bird",@"Fish",@"Cat",@"Frog", nil];
NSArray *arrayWithoutDuplicates = [[NSSet setWithArray:arrAnimals] allObjects];

answered Jul 07 '14 at 12:07

Adam

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This code works for me. This will returns the array of after removing duplicate values, without using NSPredicate. Thanks – Apoorv Jul 07 '14 at 12:38

score 0 · Answer 3 · answered Jul 07 '14 at 13:31

try this one with answered by @iMartin

 NSArray *arrAnimals = @[@"Cat",@"Rat",@"Fish",@"Cat",@"Fish",@"Cat",@"Cat",@"Bird",@"Fish",@"Cat",@"Frog"];

    arrAnimals= [arrAnimals valueForKeyPath:@"@distinctUnionOfObjects.self"];

    arrAnimals= [arrAnimals sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
        unichar firstChar =  [obj1 characterAtIndex:0];
        unichar secondChar =  [obj2 characterAtIndex:0];

        if ( firstChar == secondChar) {
            return NSOrderedSame;
        } else {
            if ( firstChar > secondChar) {
                return NSOrderedDescending;
            } else {
                return NSOrderedAscending;
            }

        }

    }];

How to sort NSArray of NSStrings using NSPredicate?

3 Answers3