Although many compiler directives exist in the Xcode wild, many developers rarely move past #define (to create macros) or #pragma mark (to add bookmarks). There’s so much more you can do. Compiler directives are language add-ons that specify how Xcode processes its input. Xcode’s Clang compiler offers a rich suite of possibilities. This quick write-up offers a few of these directives, and you learn how they can enable you to harness warnings and errors for the greatest information impact.