sorting NSmutable array contains object according to double value

Question

I want to order NSMutableArray contain objects according to two of object property one of them has double type second has NSString ?

I tried to use this method but I got exception :

NSString * LASTNAME = @"lastName";
NSString * GRADE = @"grade";

NSSortDescriptor *lastDescriptor =
    [[NSSortDescriptor alloc]
        initWithKey:LASTNAME
          ascending:YES
           selector:@selector(localizedCaseInsensitiveCompare:)];

NSSortDescriptor *firstDescriptor =
    [[NSSortDescriptor alloc]
        initWithKey:GRADE
          ascending:YES
           selector:@selector(localizedCaseInsensitiveCompare:)]];

NSArray * descriptors =
   [NSArray arrayWithObjects:lastDescriptor, firstDescriptor, nil];
NSArray * sortedArray =
   [students sortedArrayUsingDescriptors:descriptors];

@interface Student : NSObject
{
    NSString * firstName;
    NSString * lastName;
    double grade;
}

Chuck · Accepted Answer · 2012-05-18 04:10:40Z

1

NSNumber doesn't respond to localizedCaseInsensitiveCompare:. You want just plain compare: for the number.

answered May 18, 2012 at 4:10

Chuck

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6 Comments

kartal Over a year ago

should i make grade NSNumber instead of double I tried compare but I got exception again?

Chuck Over a year ago

@salamonti: Key-Value Coding will return an NSNumber for a double, so that wouldn't be a problem. What is the exact exception you're getting?

kartal Over a year ago

you are right and I solved it by remove compare also so it will be NSSortDescriptor *firstDescriptor = [[NSSortDescriptor alloc] initWithKey:GRADE ascending:YES]];

rdelmar Over a year ago

Really? That worked? I thought that compare: was the default, so removing compare: shouldn't do anything, should it?

kartal Over a year ago

@rdelmar i didn't see the result yet if it was working write I will add it as right answer

|

rdelmar · Accepted Answer · 2012-05-18 04:53:38Z

1

Numbers don't have a case, try using compare: for GRADE

After Edit: You didn't say what error you got. Did the code you posted even compile? You have a typo in your firstDescriptor -- one too many "]" at the end of the method. You probably fixed that when you took out the compare: (which shouldn't have fixed anything).

edited May 18, 2012 at 4:53

answered May 18, 2012 at 4:10

rdelmar

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Comments

kartal · Accepted Answer · 2012-05-18 05:21:09Z

0

Remove localizedCaseInsensitiveCompare

NSSortDescriptor *firstDescriptor =
    [[NSSortDescriptor alloc]
        initWithKey:GRADE
          ascending:YES]];

answered May 18, 2012 at 5:21

kartal

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1 Comment

rdelmar Over a year ago

This code will not compile -- once again, you have an extra "]" at the end.

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