NSSortDescriptor Example

You  have a class Human with following structure:

@interface HumanClass : NSObject {

    

    NSString *name;

    NSString *lastname;

    NSInteger age;

    NSString * city;

    NSDate *birthDate;

    

}

Our array with objects of HumanClass looks like following

Reetu  raj ,45,  NY,  01.05.2011|15:46:40

Mike  Hemington ,15,  New Delhi,  01.05.2011|16:05:00

pinku  Ji ,25,  chandigarh,  01.05.2011|16:20:00

anita  singh ,35,  ramgarh,  09.04.2011|16:00:00

Ankita  Singh ,55,  barbados,  01.05.2011|16:03:20

Ram  Malhotra ,27,  New York,  02.05.2011|19:33:20

Sita  Raman ,34,  London,  01.05.2011|18:33:20

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Lets sort it by date by applying a date sort descriptor. Note that we have given the key  birthDate(HumanClasss's member var string)

        NSSortDescriptor *sortDesc = [[NSSortDescriptor alloc] initWithKey:@"birthDate" ascending:YES selector:@selector(compare:)];

    [humanArray sortUsingDescriptors:[NSArray arrayWithObject:sortDesc]];

    [self printHumanArray];

You can change ascending  to NO to make it descending .Result looks like following:

anita  singh ,35,  ramgarh,  09.04.2011|16:00:00

Reetu  raj ,45,  NY,  01.05.2011|15:46:40

Ankita  Singh ,55,  barbados,  01.05.2011|16:03:20

Mike  Hemington ,15,  New Delhi,  01.05.2011|16:05:00

pinku  Ji ,25,  chandigarh,  01.05.2011|16:20:00

Sita  Raman ,34,  London,  01.05.2011|18:33:20

Ram  Malhotra ,27,  New York,  02.05.2011|19:33:20


__________________________________________________________________________________________

       sortDesc = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES selector:@selector(compare:)];

    [humanArray sortUsingDescriptors:[NSArray arrayWithObject:sortDesc]];

    [self printHumanArray];

Our result looks like following with array sorted by name but sorting is case-sensitive.

Ankita  Singh ,55,  barbados,  01.05.2011|16:03:20

Mike  Hemington ,15,  New Delhi,  01.05.2011|16:05:00

Ram  Malhotra ,27,  New York,  02.05.2011|19:33:20

Reetu  raj ,45,  NY,  01.05.2011|15:46:40

Sita  Raman ,34,  London,  01.05.2011|18:33:20

anita  singh ,35,  ramgarh,  09.04.2011|16:00:00

pinku  Ji ,25,  chandigarh,  01.05.2011|16:20:00


__________________________________________________________________________________________

        sortDesc = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES selector:@selector(caseInsensitiveCompare:)];

    [humanArray sortUsingDescriptors:[NSArray arrayWithObject:sortDesc]];

    [self printHumanArray];

We created case-insensitive sorting descriptor for name and our result looks like following:

anita  singh ,35,  ramgarh,  09.04.2011|16:00:00

Ankita  Singh ,55,  barbados,  01.05.2011|16:03:20

Mike  Hemington ,15,  New Delhi,  01.05.2011|16:05:00

pinku  Ji ,25,  chandigarh,  01.05.2011|16:20:00

Ram  Malhotra ,27,  New York,  02.05.2011|19:33:20

Reetu  raj ,45,  NY,  01.05.2011|15:46:40

Sita  Raman ,34,  London,  01.05.2011|18:33:20


__________________________________________________________________________________________

We want to sort by first name as well as last name but by general convention it should be localized and case-insensitive. So our descriptor looks like following

      sortDesc = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES selector:@selector(localizedCaseInsensitiveCompare:)];

    NSSortDescriptor *sortDesc1 = [[NSSortDescriptor alloc] initWithKey:@"lastname" ascending:YES selector:@selector(localizedCaseInsensitiveCompare:)];

    [humanArray sortUsingDescriptors:[NSArray arrayWithObjects:sortDesc,sortDesc1, nil]];

    [self printHumanArray];

And our result looks like following

anita  singh ,35,  ramgarh,  09.04.2011|16:00:00

Ankita  Singh ,55,  barbados,  01.05.2011|16:03:20

Mike  Hemington ,15,  New Delhi,  01.05.2011|16:05:00

pinku  Ji ,25,  chandigarh,  01.05.2011|16:20:00

Ram  Malhotra ,27,  New York,  02.05.2011|19:33:20

Reetu  raj ,45,  NY,  01.05.2011|15:46:40

Sita  Raman ,34,  London,  01.05.2011|18:33:20


__________________________________________________________________________________________

We want to sort by multiple keys, first by city followed by name, so our descriptor looks like following:

       sortDesc = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES selector:@selector(caseInsensitiveCompare:)];

    sortDesc1 = [[NSSortDescriptor alloc] initWithKey:@"city" ascending:YES selector:@selector(caseInsensitiveCompare:)];

    [humanArray sortUsingDescriptors:[NSArray arrayWithObjects:sortDesc1,sortDesc, nil]];

    [self printHumanArray1];

And our result looks like following. Note I am using another method(printHumanArray1) to print the values in this code snippet.

barbados, Ankita  Singh ,55, 01.05.2011|16:03:20

chandigarh, pinku  Ji ,25, 01.05.2011|16:20:00

London, Sita  Raman ,34, 01.05.2011|18:33:20

New Delhi, Mike  Hemington ,15, 01.05.2011|16:05:00

New York, Ram  Malhotra ,27, 02.05.2011|19:33:20

NY, Reetu  raj ,45, 01.05.2011|15:46:40

ramgarh, anita  singh ,35, 09.04.2011|16:00:00






HERE IS SAMPLE CODE DOWNLOAD LINK