CMAKE_HOST_APPLE

From Get docs
Cmake/docs/3.21/variable/cmake host apple


CMAKE_HOST_APPLE

True for Apple macOS operating systems.

Set to true when the host system is Apple macOS.

© 2000–2021 Kitware, Inc. and Contributors
Licensed under the BSD 3-clause License.
https://cmake.org/cmake/help/v3.21/variable/CMAKE_HOST_APPLE.html