Question

Is there any way I could pass an object method instead of a function to a function wanting a SCNetworkReachabilityCallBack as its argument?

Here is how SCNetworkReachabilityCallBack is defined:

typedef void (*SCNetworkReachabilityCallBack)   (
                        SCNetworkReachabilityRef    target,
                        SCNetworkReachabilityFlags  flags,
                        void                *info
                        );

Answer 1

Pass a block that sends the message, then have your C callback execute the block! 😀

Basically, the C callback is going to act as glue code. Since an Objective-C method’s IMP will never be of a type compatible with the callback, you are always going to need at least one level of indirection before you get to an Objective-C message dispatch. If you need to carry more state than just the object, a block may help you, but that C function stub isn’t going anywhere.