How to set object count to zero(or some value) in NSCountedSet?

Question

I have following NSCountedSet

<NSCountedSet: 0x53dfc0> (item1 [2000], item2 [9000], item3 [200], item4  [3000])

Now i want to remove item1 object from my set.
one solution is

while([mySet countForObject:item1])
 [mySet removeObject:item1];

Output:

<NSCountedSet: 0x53dfc0> (item2 [9000], item3 [200], item4  [3000])

or i want to remove only 1000 item1 object from my set.

    NSUInteger count = [mySet countForObject:item1];
    while(count)
    {
     [mySet removeObject:item1];
     --count;
    }

Output:

<NSCountedSet: 0x53dfc0> (item1 [1000], item2 [9000], item3 [200], item4  [3000])

is there any better solution for this ?

if you know the object "item1", you can call directly "removeObject" without having the loop over mySet. — WhiteTiger, May 28 '12 at 13:13
@WhiteTiger [removeObject:](https://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSCountedSet_Class/Reference/Reference.html) decrements the count associated with NSCountedSet. — Parag Bafna, May 28 '12 at 13:16

Paul.s · Accepted Answer · 2012-05-28T13:30:31.397

2

You could filter with a predicate

[mySet filterUsingPredicate:[NSPredicate predicateWithFormat:@"self != %@", item1]];

edited May 28 '12 at 13:30

answered May 28 '12 at 13:23

Paul.s

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is there any way to reduce count of object? – Parag Bafna May 28 '12 at 13:53
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Sounds like you need to make your own object which can use an NSMutableSet behind the scenes but give you the added behaviour you want... – Paul.s May 28 '12 at 13:55

score 0 · Answer 2 · answered May 28 '12 at 13:21

0

I do not think you understand the problem, so I get these results:

<NSCountedSet: 0x6d9ee40> (two [1], three [1], one [1], four [1])

[mySet removeObject:@"one"];

<NSCountedSet: 0x6d9ee40> (two [1], three [1], four [1])

answered May 28 '12 at 13:21

WhiteTiger

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Stick `[mySet addObject:@"one"];` before your `removeObject:` to see this does not work... – Paul.s May 28 '12 at 13:37
@WhiteTiger your set contain only one [1](count is 1), i have item1 [2000] (count is 2000). – Parag Bafna May 28 '12 at 13:43
i hadn't realized you could have the possibility of having duplicate items – WhiteTiger May 28 '12 at 13:46
1

@WhiteTiger: Such is the purpose of a counted set: it tells you how many of each item is in it. Other kinds of sets do not allow duplicates; every item is either in a non-counted set or not. – Peter Hosey May 28 '12 at 23:53

score 0 · Answer 3 · answered May 28 '12 at 17:51

NSCountedSet does not offer methods to modify the count of a certain object by a certain amount (a pity really).

If speed is not an issue you can used the methods you described above. However if you need something else: subclassing NSMutableSet to provide this "counting" functionality is probably your best option.

How to set object count to zero(or some value) in NSCountedSet?

3 Answers3