CMake leaves ARC off on Xcode projects and apps leak memory.
The following attribute on Xcode projects defaults to NO. In my case, my texture viewer was leaking 100's of MB of MTLTexture objects when I would load new ones, and then I realized it was because of this. ARC has been a requirement for over 7 years now, so I'd recommend that this be enabled by default. Most macOS and iOS apps don't function properly without this set. And yes, Xcode should also likely not default to this being NO.
XCODE_ATTRIBUTE_CLANG_ENABLE_OBJC_ARC YES