Question

I dont think I’ve understood C well enough.

In my codes, added a call back method.

And inside the method, I want to be able call a method that beings to the instance. I tried [self methodName] but I’m told ‘self is an undeclared identifier`.

Added code snippets:

@implementation TheClass


static void audioRouteChangeListenerCallback (
                                       void                      *inUserData,
                                       AudioSessionPropertyID    inPropertyID,
                                       UInt32                    inPropertyValueSize,
                                       const void                *inPropertyValue) 
{

    .
    .
     //trying to call a instance method of TheClass here.
}

Answer 1

You cannot use self in a plain C function, it doesn’t belong to any Objective-C instance (that’s the difference between a function and a method).

For callbacks that are supposed to interact with Objective-C, you would usually pass a pointer to your object when you set up the callback. In this case, inUserData is probably something that you can set yourself when registering the callback.