问题
I want to use the object's reference value as a key into a dictionary, as opposed to a copy of value of the object. So, I essentially want to store an object associated with a particular instance of another object in a dictionary and retrieve that value later.
Is this possible? Is it completely against the idea of NSDictionary? I can tell that I am probably approaching this the wrong way because the dictionary wants me to implement NSCopying on the object itself, which doesn't really make sense in terms of what I'm doing. I can see that what I should really be doing is wrapping the pointer value, but that seems a little mad.
Advice would be appreciated.
回答1:
I think you can use [NSValue valueWithPointer:object].
回答2:
NSMutableDictionary has been designed to only deal with Objective-C object instances. For example, when you call setObject:forKey: method calls copyWithZone: on the key and retain on the value.
If you want to have a dictionary structure and to be able to deal with arbitrary key and value, then you can go with CFMutableDictionary. You can describe precisely what is done with key and values; it is flexible enough to deal with arbitrary pointer or event char * strings.
回答3:
This did the trick for me
aDictionary[@((intptr_t)object)] = ...;
来源：https://stackoverflow.com/questions/2708168/object-pointer-value-as-key-into-dictionary