xcconfig

xcconfig is a plain text configuration file used by Xcode to specify build settings for a project or target. Each line typically assigns a value to a build setting, using a key = value syntax. The files enable centralized, reusable control of compiler flags, preprocessor definitions, code signing, search paths, and other configuration details across configurations such as Debug and Release. Comments are supported, commonly using //, and values can reference inherited settings with $(inherited) to preserve and extend values from higher levels.

xcconfig files are commonly organized per configuration and can be combined to manage settings across multiple targets. They can include other files or be layered to compose complex configurations. This modular approach helps teams avoid duplicating settings in multiple targets and simplifies bulk updates. Typical settings found in xcconfig files include ADHOC flags, optimization levels, bitcode, Swift version, and various path and signing options. Because they are plain text, they integrate well with version control and automated build processes.

In Xcode, developers apply an xcconfig file by assigning it as the base configuration for a project or specific build configurations (such as Debug or Release) in the project’s Build Settings. Individual targets can have their own base configurations, while per-target overrides can still be specified in the build settings UI or in additional xcconfig files. The approach is widely used to improve consistency, reduce duplication, and streamline configuration management across large projects.