CMAKE_OSX_DEPLOYMENT_TARGET — CMake 3.10.2 Documentation

# CMAKE_OSX_DEPLOYMENT_TARGET

Specify the minimum version of OS X on which the target binaries are to be deployed. CMake uses this value for the `-mmacosx-version-min` flag and to help choose the default SDK (see `CMAKE_OSX_SYSROOT`).

If not set explicitly the value is initialized by the `MACOSX_DEPLOYMENT_TARGET` environment variable, if set, and otherwise computed based on the host platform.

The value of this variable should be set prior to the first `project()` or `enable_language()` command invocation because it may influence configuration of the toolchain and flags. It is intended to be set locally by the user creating a build tree.

This variable is ignored on platforms other than OS X.