i cannot remove duplicate objects in a NSArray iphone

Question

I'm going crazy right now. I have a NSMutableArray with a bunch of Person objects. I want to remove the duplicated objects but it won't work. This is what i got:

NSMutableArray *withoutDoubles =[[NSMutableArray alloc]init];
    NSArray *temp = [[NSArray alloc] initWithArray:tempResults];
    for (Person *person in temp) {
        if(![withoutDoubles containsObject:person]) {
            [withoutDoubles addObject:person];
        }       
    }
    for (Person *person in withoutDoubles) {
         NSLog(@"----> %@",person.name);
    }

That is not working, i still got duplicates. I also tried:

NSArray *temp = [[NSArray alloc] initWithArray:tempResults];
NSSet *set = [NSSet setWithArray:temp];

But it didn't work either. I need some help here.

Thanks in advance.

Check http://stackoverflow.com/questions/1025674/the-best-way-to-remove-duplicate-values-from-nsmutablearray-in-objective-c — Jhaliya - Praveen Sharma, Jun 29 '11 at 09:53

score 2 · Answer 1 · answered Jun 29 '11 at 10:00

2

You can have problem with isEquals: method. Two objects are equals, when both have same hash. isEquals: documentation

answered Jun 29 '11 at 10:00

MarrLiss

808
5
10

score 1 · Accepted Answer · answered Jun 29 '11 at 10:09

If your definition of a duplicate is two separate Person objects whose properties are set the same then the best way to achieve this is to override these two methods in your Person object

- (BOOL)isEqual:(id)anObject
- (NSUInteger)hash

which will allow you to properly achieve the compare.

You would then need to do the following

for (Person *personToTest in temp) {
    BOOL duplicate = NO;
    for (Person *person in withoutDoubles) {
        if ([personToTest isEqual:person]) {
            duplicate = YES;
            break;
        }
    }
    if (!duplicate) {
        [withoutDoubles addObject:personToTest];
    }      
}

score 0 · Answer 3 · answered Jun 29 '11 at 09:58

0

Are you sure that persons with the same name are really the same object (i.e. the pointer is pointing to the same address)?

answered Jun 29 '11 at 09:58

dasdom

13,975
2
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58

score 0 · Answer 4 · answered Jun 29 '11 at 10:02

0

what is person ? any custom object ??? if so then add any unique ID in that class and then compare with that ID.

answered Jun 29 '11 at 10:02

Maulik

19,348
14
82
137

yes, it is a custom object. Should i override the `isEquals` method in the person class? – madcoderz Jun 29 '11 at 10:11
then try to access the object's unique field that is already available in ur mutable array and compare it with new object's unique filed.. – Maulik Jun 29 '11 at 10:14
ok i give up, i tried to do as you said but it didn't work i trid this `for (Person *compareThis in tempResults) { for (Person *toThis in withoutDoubles) { if (compareThis._id != toThis._id){ [a addObject:toThis]; } } } ` can you provide an example? – madcoderz Jun 30 '11 at 10:18

score 0 · Answer 5 · answered Jun 29 '11 at 10:08

Try this one, i hope this may help you

    NSArray *copy = [mutableArray copy];
NSInteger index = [copy count] - 1;
for (id object in [copy reverseObjectEnumerator]) {
    if ([mutableArray indexOfObject:object inRange:NSMakeRange(0, index)] != NSNotFound) {
        [mutableArray removeObjectAtIndex:index];
    }
    index--;
}
[copy release];

score 0 · Answer 6 · answered Jun 29 '11 at 10:11

Well you could just do it like this:

NSMutableArray*array1 = [NSMutableArray arrayWithObjects:person,person1,person2,nil];
NSMutableArray*array2 = [NSMutableArray arrayWithObjects:person1,person2,person,nil];

for (Person*person in array1)
{
    if ([array2 containsObject:person])
    {
         [array2 removeObject:person];
    }
}

This will remove all duplicates found in array2. You can also use isEqual: to compare the objects, that's up to you. Replace array1 and array2 with your two arrays and give it a go.

score 0 · Answer 7 · answered Aug 11 '11 at 09:21

0

One liner: uniqueArray = [[NSSet setWithArray:temp] allObjects];

answered Aug 11 '11 at 09:21

REALFREE

4,378
7
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This does not preserve the order. – Lance Feb 05 '14 at 23:24

i cannot remove duplicate objects in a NSArray iphone

7 Answers7

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