Not sure how to declare a variable (in MIDIPortConnectSource) for use with other methods in a class

I am trying 开发者_Go百科to use this in a class.

 OSStatus MIDIPortConnectSource(
                                   MIDIPortRef     port,
                                   MIDIEndpointRef source,
                                   void*           connRefCon)

I'm not sure what connRefCon should be declared as in the header file. Can anyone help me with this?

That is for your use. It is passed to your MIDIReadProc to identify the source. If you don't need to identify the source you can set it to NULL.