问题 I'm building an application that needs to check what version of OS X is installed on a Mac. It is built against 10.9 Mavericks, but all of the Swift APIs are pretty much 10.10 only. I'm trying to use the following, however it does not compile against the 10.9 SDK since it does not have these APIs, I know how to use if #available(OSX 10.10, *) to conditionally compile as per the different versions, however because NSProcessInfo is a 10.10+ API I can't use it to check to see if the Mac is