when developing for long-term use, you want to use APIs that aren’t likely to be removed soon, a.k.a. “deprecated”.
So, don’t use downward compatible calls below a point you really aim for.
XCode helps with compiler warnings about “deprecated” calls – if “Project -> Edit Project Settings -> GCC_WARN_ABOUT_DEPRECATED_FUNCTIONS” is set:
But be careful, this complains e.g. …