___isPlatformVersionAtLeast link error with old Xcode due to @available

[seanm]

___isPlatformVersionAtLeast link error with old Xcode due to @available

[jwwalker]

How old a version of Xcode are we talking? I didn't think @available was a particularly recent feature. I'm reluctant to change it, as that seems like the approach that Apple always recommends. It's also easier to read than some weird AppKit version number.

Checking for 10.15 instead of 10.7 is deliberate. Although convertRectToBacking may have worked earlier, it wasn't necessary until a change in the implementation of NSOpenGLView in Catalina.

[seanm]

Xcode 10.1, the newest possible on macOS 10.13.x, released 2018-10-30.

It's not that Xcode 10.1 doesn't support @available, it's that building a lib on a newer Xcode, then using that lib with an older Xcode fails. Others have the same issue, ex: https://developer.apple.com/forums/thread/123003

In my case, to build Quesa as a fat binary, I have to use Xcode 12. Since Quesa changes rarely, I commit the resulting libQuesa.a to my source control, then bots of several versions of macOS build my own code nightly against it.

[seanm]

Here's a fix: #11

[jwwalker]

I pushed a revision that puts the version test in a new function, so that I can document it in one place. By the way, the use of the floor function in your pull request was unnecessary.

[seanm]

Thanks!

flooring NSAppKitVersionNumber is idiomatic, and old habits die hard. :)