New in version 3.11.
If enabled, the Xcode generator will generate only a single Xcode project file for the topmost project() command instead of generating one for every project() command.
This could be useful to speed up the CMake generation step for large projects and to work-around a bug in the ZERO_CHECK logic.
© 2000–2020 Kitware, Inc. and Contributors
Licensed under the BSD 3-clause License.
https://cmake.org/cmake/help/v3.19/variable/CMAKE_XCODE_GENERATE_TOP_LEVEL_PROJECT_ONLY.html