What is the tutorial you are following?
I have not used openFrameworks, but your Visual Studio example has a C++ file, the .cpp file, and your Xcode file has an Objective-C file, the .m file. You either need a C++ file or an Objective-C++ file (extension .mm) to get the code to work, as I doubt openFrameworks supports Objective-C.
Have you gone through the openFrameworks Xcode setup tutorial?
https://openframeworks.cc/setup/xcode/
You will have a better chance of getting an answer at the openFrameworks forums since I doubt very few people here use openFrameworks. I never heard of it until I read your question.
https://forum.openframeworks.cc
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Business & Education
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General
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