Last time I played with getting a moderately complex old (Jaguar/Panther/Tiger era) Obj-C/Cocoa OS X app building on modern macOS, fixing the build-stopper erro

Last time I played with getting a moderately complex old (Jaguar/Panther/Tiger era) Obj-C/Cocoa OS X app building on modern macOS, fixing the build-stopper errors didn't take too long but there was a mountain of deprecation warnings, despite everything seemingly working as expected. That was a few years ago though so I wouldn't be surprised if some of those deprecations have turned to errors in the meantime.