Hey Luigi and Joshua!
Thank you very much for your replies. Unfortunately I failed on the way of getting the XCode Project configured to meet all changes to 6.1. (the Linker Flags I had adopted already before), in other words, it got worse. I will report back in this thread on behalf of this problem once i fixed it.
Since I encountered a strange behavior of the buffer~ object in 6.1 I have to stick with the former version of the framework for further development. But maybe you can tell me whether it is connected to wrong configuration or not: Reading a simple file into a buffer (no externals in the patch yet) doesn’t update the display of the waveform object as expected, sometimes it looks like 0dB noise beeing read, sometimes it stays empty and sometimes it just works as expected. The same patch is working in Max 6.0.7. I attached the test-patch for this problem.