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?

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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.