Question

I’m trying to use a class as a key in an NSDictionary. I looked at the answer to this question and what I have is pretty much the same; I’m using setObject: forKey:. However, XCode complains, saying Incompatible pointer types sending 'Class' to parameter of type 'id<NSCopying>'. The call I have is:

[_bugTypeToSerializerDictionary setObject: bugToStringSerializer 
                                forKey: [bugToStringSerializer serializedObjectType]];

bugToStringSerializer is an instance of BugToStringSerializer whose concrete implementations implement serializedObjectType. An example of a concrete implementation looks like this:

- (Class) serializedObjectType {
    return [InfectableBug class];
}

What am I doing wrong here?

Answer 1

(It seems that classes do conform to NSCopying, however their type is not id <NSCopying>.) Edit: classes do not conform to protocols. Of course the essential is that classes respond to the copy and copyWithZone: messages (and that’s why you can safely ignore the warning in this case). Their type is still not id <NSCopying>.) That’s why the compiler complains.

If you really don’t want that ugly warning, just perform an explicit type conversion:

[dictionary setObject:object forKey:(id <NSCopying>)someClass];