I'm writing a simple Command line application on macOS with code using C++, using a API called 'std::to_chars' from charconv void foo(void) {   if (__builtin_available(macOS 10.15, *))   {     char buffer[10];     std::to_chars_result tcr = std::to_chars( buffer, buffer+5, 5 ); #pragma unused (tcr)   }else{     return;   }     } Since Xcode complains main.cpp:19:41: error build: 'to_chars<int, 0>' is unavailable: introduced in macOS 10.15 I wrapped the code with an availability check API in C++, __builtin_available(macOS 10.15, *)) But even with this availability check API, Xcode still failed to compile. Anyone knows why?

I followed apple's demo application to create an audio server plugin named NullAudio. However, since the code is written in C with some COM interfaces, it is hard for a Swift Programmer. So I want to attach XCode to the Null Audio Plugin to take a look at the method calls. I googled and found the audio server plugin maybe debug in this way: Note the BGMDevice is another audio server plugin they created. So I followed, xcode attaches to coreaudiod process. But any breakpoint in the code just go grey, how can I make the break point active?