Because of other issues, I am having to use Xcode 9.4.1 for my app. However, there is one function that depends on a third-party tool which fails on macOS 10.14. I'd like to disable the command that causes the failure at run-time, so I'm looking for a way to tell whether I'm running on a system later than 10.13. Normally I've done that by checking availability of a particular function, but that depends on having a later SDK. Is there a different way to do it? The code that needs to check is in Obj-C.

(This is only a temporary solution, while I try to get the tool replaced, and complete the rewrite of the whole app into Swift.)

Thanks in advance,
John
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John Brownie
Mussau-Emira language, New Ireland Province, Papua New Guinea
Kouvola, Finland