What is an NSConcreteValue and how do I extract its value?

Question

I have a library where I am receiving NSConcreteValue and I have no idea how to deal with it. I know the object I am supposed to get is a boolean, so how do i extricate the real value?

Answer 1

That’s a private class that’s sometimes (or all the times?) used behind the scenes when you work with NSValue. Or at least that’s my impression. I think you should be able to cast to NSValue:

// assuming value is of type “id”
NSAssert([value isKindOfClass:[NSValue class]],
    @"Sorry, I was wrong. Maybe try anyway?");
NSAssert(strcmp(@encode(BOOL), [value objCType]) == 0,
    @"The value does not seem to hold a BOOL.");
BOOL unwrappedValue;
[value getValue:&unwrappedValue];

…or something like that, I’m making this up :-)