I'd like to be able to build my project and open it in Xcode, without having to manually set variables through the Xcode UI. I started using Cordova's buildConfig parameter to specify some settings (especially using the legacy build system and setting the Swift version), and that works for command line builds, but they don't carry over into Xcode project files.
I was using a custom hook to modify build settings in my project.pbxproj file, but I was hoping this isn't necessary - just figuring out what the setting is called and which file it's in is a pain.
I haven't been able to find it in the Cordova documentation, so I'm asking... does Cordova have a way of persisting these build settings in Xcode?
You said that you tried using a custom hook, and this method is completely valid. You do not have to manually edit the file yourself if that is what you were doing. Using a hook and using the xcode npm package will make this a lot easier. In this case you only need to specify the key and value you want to change in the project file. If you want to change your workspace configuration (build system options) you would want to use the plist npm package. Using these tools it might be less of a pain for you, if you find it easier than the other answer posted.
Example editing the project: