This is a blank single-view-controller iOS app, linked against to a C++ static libraries, plus a a simple unit xctest. We use CMake to create an Xcode-friendly out-of-source build system. In another word, the build system is maintained by CMakeLists file,instead of a configured .xcodeproj file.
This CMake project can build the executable BenchmarkApp which is linked to the static C++ library 'mbgl-benchmark'. CMakeLists.txt files are the only build configuration kept in source control. This is in contrast to committing the .xcodeproj directory which includes the backing XML, which is nonsensically hard to edit by hand.
The test instantiates ObjC object of class IosTestRunner from the app, the class will instantiates a C++ object from the linked library mbgl-benchmark and calls running benchmark function on it. It subsequently deletes the C++ object pointer. In the end, the test will check the existence of test report, which is a json file that attach to xctest result.