Re: CoreBase toll-free bridging

[Luboš Doležel]

Hi again,

I was investigating what approach Apple took in solving a problem with 
calling CF functions on ObjC objects, which return an autoreleased 
object in ObjC, but clearly shouldn't do so when using the CF call.

For instance, you have to release the result of 
CFTimeZoneCopyLocalizedName() yourself, but you mustn't do that with 
[NSTimeZone localizedName:locale:], since that will be autoreleased.

An ordinary CF_OBJC_FUNCDISPATCH from the former to the latter therefore 
doesn't work correctly "out of box". Apple's source code showed no 
solution at all, but still on OS X it seemed to work correctly...

So I took my disassembler again and voilá! The source code released by 
Apple under the 10.8 section *doesn't match* the OS X 10.8 binares. In 
CFTimeZone's case it doesn't match it at all.

CFTimeZone on OS X is *entirely* built on top of NSTimeZone.

CFTimeZoneCopyLocalizedName() actually does something like this:

=====
_CFAutoreleasePoolPush();
NSString* retval = [(NSTimeZone*)tzSelf localizedName: arg1
                                               locale: arg2];

CFRetain(retval);
_CFAutoreleasePoolPop();

return retval;
=====

Which explains why it doesn't exhibit the above described problem as one 
would expect from their source code.

So Chan, you were partially right. But I've checked other types and it 
seems it is the case only in CFTimeZone.

--
Luboš Doležel