If I understand this correctly, copy enforces the setter to create a copy of the object passed in. However, if I use it together with readonly, there won't be a setter. So is my assumption correct, that combining @property (copy, readonly) doesn't make any sense or am I missing something?
I think, if I saw such a property, on read, I would expect to receive a distinct returned object to the ivar unless the returned object was advertised to be immutable.
If I have
@property (readonly, copy) NSMutableArray* foo;
and I do this:
NSMutableArray* myFoo = [theObject foo];
[myFoo addObject: @"string"];
NSMutableArray* myOtherFoo = [theObject foo];
I would expect myOtherFoo not to have the extra string in it that myFoo has.
Note: I haven't verified this yet.
I have checked it now and my expectation is incorrect. I think I would regard that as a bug.