Question

I hope the title is not too misleading… 🙂

I play a system sound and add the SoundCompletion-Callback to it like so:

AudioServicesAddSystemSoundCompletion(soundID, NULL, NULL, completionCallback, (__bridge_retained void *)self);

Whereas «self» is a simple NSObject

In the completion callback I try to call the playing routine again:

I had to add the __bridge_transfer and the __bridge_retained to the casts, otherwise I get errors, crashes, or other unexpected behaviour.

But the whole thing doesn’t work despite all that.

I store the sounds to play in an NSMutableArray, grab the first entry of the array and play it, add the sound completion and hope stuff happens.
But – with all that retained-transfer stuff, the NSMutableArray is empty on the second call…

Here’s the code:

static void completionCallback (SystemSoundID  mySSID, void *myself) {

    NSLog(@"Audio callback");

    AudioServicesRemoveSystemSoundCompletion (mySSID);
    AudioServicesDisposeSystemSoundID(mySSID);

    [(__bridge_transfer Speaker *)myself speakCharacter];

    CFRelease(myself); // I heard I need this?

}

-(void)speakCharacter{

    if([sounds count] > 0){

        NSString *soundToPlay = [sounds objectAtIndex:0];
        [sounds removeObjectAtIndex:0];
        NSLog(@"TxtToSpeak %@", soundToPlay);
        CFURLRef        soundFileURLRef;
        NSURL *path = [[NSBundle mainBundle] URLForResource:[soundToPlay uppercaseString] withExtension:@"aif"];
        soundFileURLRef = (__bridge CFURLRef)path;
        SystemSoundID soundID;
        AudioServicesCreateSystemSoundID(soundFileURLRef, &soundID);
        AudioServicesAddSystemSoundCompletion(soundID, NULL, NULL, completionCallback, (__bridge_retained void *)self);
        AudioServicesPlaySystemSound (soundID);
    }
}

[EDIT] – ANSWERING MY OWN QUESTION:

Always nice to find it out myself 🙂

Turns out, I was almost there.

The call to set up the callback is as follows:

AudioServicesAddSystemSoundCompletion(soundID, NULL, NULL, completionCallback, (__bridge_retained void *)self);

Then, in the callback-function, I do this:

myClass *theClass = (__bridge myClass *)myself;
    CFRelease(myself);
    [theClass playNextSound]; // The routine that plays the sounds

And it works…

Answer 1

I couldn’t answer my own question since I was too fast for StackOverflow – so just to make this complete, I add the answer again 🙂

Turns out, I was almost there.

The call to set up the callback is as follows:

AudioServicesAddSystemSoundCompletion(soundID, NULL, NULL, completionCallback, (__bridge_retained void *)self);

Then, in the callback-function, I do this:

myClass *theClass = (__bridge myClass *)myself;
CFRelease(myself);
[theClass playNextSound]; // The routine that plays the sounds

And it works…