Check duplicate property values of objects in NSArray

Question

I have an NSArray containing objects with a size property.

How can I check if the NSArray has two objects with the same value for size?

Can I do something like:

int i = 0;
for (id item1 in myArray) {
    NSDecimalNumber *size1 = [item1 size];

    for (id item2 in myArray) {
        NSDecimalNumber *size2 = [item2 size];

        if ([size1 isEqual:size2]) {
            i ++;
        }
    }
}

if (i > [myArray count]) {
    NSLog(@"Duplicate Sizes Exist");
}

Or is there an easier way?

Answer 1

Try this code:

NSSet *myset = [NSSet setWithArray:[myarray valueForKey:@"size"]];
int duplicatesCount = [myarray count] - [myset count];

size here is the object property.

Answer 2

Use NSCountedSet. then add all your objects to the counted set, and use the countForObject: method to find out how often each object appears in your array.

You can check this link also how-to-find-duplicate-values-in-arrays

Hope it helps you

Answer 3

Probably simplest is to sort the array based on the size field and then step through the sorted list looking for adjacent dupes.

You could also "wrap" each object in one that exports the size as its key and use a set. But that's a lot of extra allocations.

But if you only want to know if dupes exist, and not which ones they are, create an NSNumber for each object's size and insert the NSNumbers in a set. The final size will tell you how many dupes.

Answer 4

NSArray *cleanedArray = [[NSSet setWithArray:yourArraywithDuplicatesObjects ] allObjects];

Use Sets this will remove all duplicates objects.Will return NSArrayNSCountedSet and use countForObject: method to find out how often each object appears how many times.