i cannot remove duplicate objects in a NSArray iphone

问题

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.

回答1:

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];
    }      
}

回答2:

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

回答3:

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

回答4:

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

回答5:

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];

回答6:

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.

回答7:

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

来源：https://stackoverflow.com/questions/6518714/i-cannot-remove-duplicate-objects-in-a-nsarray-iphone

标签

iphone

objective-c

cocoa-touch

nsmutablearray