On Jan 20, 2014, at 2:27 PM, Michael Crawford wrote:
> I'm working on a Mac OS X product that currently runs on 10.6 through to
> 10.9. This product includes an NSColor category method named CGColor, which
> is patterned after the iOS UIColor interface and returns a CGColorRef.
>
> @interface NSColor (CGColor)
> - (CGColorRef)CGColor CF_RETURNS_RETAINED;
> @end
>
> As I'm sure you are aware, 10.8 now defines a method that does the same thing
> using the same name. I'd like to make it so that calling code doesn't have
> to distinguish between these two methods but invokes the correct one based on
> which version of the runtime is present. What is the best approach to
> solving this problem?
1) Put the method into a category in a loadable bundle. Only load that bundle
if ![NSColor instancesRespondToSelector:@selector(CGColor)].
2) Put the implementation in a function with the right signature for the IMP of
that method. At runtime, if NSColor doesn't implement the method (as above),
use the Objective-C runtime to add the method to the class with your function
as the implementation.
static CGColorRef my_NSColor_CGColor_imp(id self, SEL _cmd)
{
// ...
}
Early in app start-up:
if (![NSColor instancesRespondToSelector:@selector(CGColor)])
class_addMethod([NSColor class], sel_registerName("CGColor"),
(IMP)my_NSColor_CGColor_imp, "@@:");
> On Jan 23, 2014, at 4:02 AM, Greg Parker <gpar...@apple.com> wrote:
>
>> On Jan 20, 2014, at 12:27 PM, Michael Crawford <michaelacrawf...@me.com>
>> wrote:
>>> I also realize that the 10.8 version returns an autoreleased object whereas
>>> the version written a couple of years ago must have the resulting reference
>>> freed by the caller. I'm not sure how Apple pulls that off with a CF
>>> reference but I'd love to have a solution for that as well.
>>
>> The NS/CF bridge means that calling autorelease on a CF object works fine.
>
> Thanks for the reply, Greg. I running with ARC enabled. The compiler flags
> any calls to autorelease. What am I missing?
You can compile individual translation units with ARC disabled.
Regards,
Ken
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