是否可以有两个具有相同值的不同NSNumber对象？

Question

I wanted to have a list or set which might contain two NSNumbers with the same integer value but it seems that memory is optimised so they are the same object.
eg

NSNumber* n1=[NSNumber numberWithInt:10];
NSNumber* n2=[NSNumber numberWithInt:10];

then n1==n2;

Is there a way round this so that n1!=n2 ?

Answer 1

Not really. Cocoa keeps a cache of small numbers (IIRC those that represents integers from 0 to 12), and tagged pointers will also prevent that.

If you really need that, one option is to create a class that boxes NSNumber instances. In this way you can guarantee that different instances of your class will have different addresses.