I have developed my own cross-platform GUI framework in C++ and I am looking to add support for Mac. I have tried to stay as close to the metal as possible, using GDI+ on Windows and X11 / XRender on Linux. Years ago I had a precursor to this system working with Cocoa and Quartz, which required an interface with some Objective-C code. In the latest version of Xcode I don't see any options to create an Objective-C application. Should I be creating a Swift application? If so, how do I make that interface with my C++ code? I am not interested in a GUI designer or anything like that because I am writing a general-purpose library. I just need the ability to create OSX windows and draw 2D graphics on them with the low-level system commands. Please advise.

It appears that macOS applications are ignoring the current working directory set by Xcode. Here is a simple Xcode project that demonstrates the problem: https://www.ultraengine.com/downloads/xcodeworkingdir.zip The application starting directory retrieved by NSFileManager:currentDirectoryPath is always "/Users/josh/Library/Containers/whatever.test/Data" even though in the product schema I have a custom working directory set to $(PROJECT_DIR). Tested on macOS Catalina with Xcode 12.2 and 11.3.1.