Calling a method from a callback function under ARC

Question

Hi All
I previously wrote some HIDManager software. The HIDManager references were done in a Objective C class so within this object you have the code:
    IOHIDManagerRegisterDeviceMatchingCallback( k8055HIDManager, k8055BoardWasAdded, (__bridge void*)self );
Which registers with the HIDManager
The Callback function which is outside the class was as follows:
static void k8055BoardWasAdded(void* inContext, IOReturn inResult, void* inSender, IOHIDDeviceRef k8055HIDDevice)
    IOHIDDeviceOpen(k8055HIDDevice, kIOHIDOptionsTypeNone);
    CCVellemanK8055Driver * k8055 = (__bridge CCVellemanK8055Driver *)inContext;
    [k8055 setHardwareConnectionStatus : YES];
Any how my problem is in converting the code to ARC as under OS X 10.9 SDK and 64bit I'm now getting a EXC_BAD_ACCESS (Code=EXC_I386_GPFLT) at this line
    CCVellemanK8055Driver * k8055 = (__bridge CCVellemanK8055Driver *)inContext;
although removing the method
[k8055 setHardwareConnectionStatus : YES];
will alow it to build but then obviously the app won't work as required.
Could someone suggest a ARC safe way of accessing the passed instance so I can again call methods on it.
Cheers
Steve

Answer 1

Try using blocks instead. This is the callback I am using for libcurl.
static size_t callback(
  void * contents, size_t size, size_t nmemb, void * context)
  size_t (^block)(void *, size_t) =
    (__bridge size_t (^)(void *, size_t))context;
  size_t result = block(contents, size * nmemb);
  return result;