Invalid conversion from... Objective-C++

Question

I just told Xcode to compile everything as Objective-C++ and now I have errors from casting.

void audioRouteChangeListenerCallback (
                                       void                      *aInUserData,
                                       AudioSessionPropertyID    aInPropertyID,
                                       UInt32                    aInPropertyValueSize,
                                       const void                *aInPropertyValue
                                       ) {

    // Ensure that this callback was invoked because of an audio route change
    if (aInPropertyID != kAudioSessionProperty_AudioRouteChange) return;

    // This callback, being outside the implementation block, needs a reference to the MixerHostAudio
    //   object, which it receives in the inUserData parameter. You provide this reference when
    //   registering this callback (see the call to AudioSessionAddPropertyListener).
    TJUSimpleSequencer *lAudioObject = (TJUSimpleSequencer *) aInUserData;

    // if application sound is not playing, there's nothing to do, so return.
    if (NO == lAudioObject.isPlaying) {

        NSLog (@"Audio route change while application audio is stopped.");
        return;

    } else {

        // Determine the specific type of audio route change that occurred.
        CFDictionaryRef routeChangeDictionary = aInPropertyValue; // !!! invalid conversion from 'const void*' to 'const __CFDictionary*'

        CFNumberRef routeChangeReasonRef =
        CFDictionaryGetValue (
                              routeChangeDictionary,
                              CFSTR (kAudioSession_AudioRouteChangeKey_Reason)
                              ); // !!! invalid conversion from 'const void*' to 'const __CFNumber*'

When i try to use static_cast<CFDictionaryRef>(aInPropertyValue), I get nothing. As though (which is probably true) I am not using it correctly.

score 1 · Accepted Answer · edited May 23 '17 at 12:13

1

Use regular C cast?

CFDictionaryRef routeChangeDictionary = ( CFDictionaryRef )aInPropertyValue;

Edit 0:

How about this for that function call (if you're sure it's a number :)

CFNumberRef routeChangeReasonRef =
    ( CFNumberRef )CFDictionaryGetValue ( ...

Edit 1:

Take a look at The Definitive C++ Book Guide and List then.

edited May 23 '17 at 12:13

Community

1
1

answered Apr 10 '11 at 02:09

Nikolai Fetissov

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ok--that worked--why doesn't static cast work? Not that i REALLY want to use it, but it doesn't make sense to me. – griotspeak Apr 10 '11 at 02:36
I'm not a Objective-C guy, but in C++ that'd be `reinterpret_cast<>` not a `static_cast<>`. – Nikolai Fetissov Apr 10 '11 at 02:52
Thanks for the update. I have already started in on the C++ primer plus – griotspeak Apr 15 '11 at 14:05

Invalid conversion from... Objective-C++

1 Answers1

Edit 0:

Edit 1: