Add a Build Configuration
Customize a set of build setting definitions across any number of targets or projects by adding a build configuration file to your project. To add a build configuration file, duplicate one of the project’s existing configurations, and modify its settings.
In the project editor, select a project.
Click Info at the top of the project editor.
In the Configurations section, click the Add button (+).
From the popup menu, select a configuration file to duplicate.
Enter a name for the new build configuration file.
Click Build Settings at the top of the project editor.
Edit the settings for your new build configuration file.
A configuration file is a plain text file with a list of build setting definitions, one per line. You can base a build configuration only on a configuration file that is in your project, not on an external file.
When you base a target or project’s build configuration on a configuration file, that build configuration automatically inherits the build setting definitions in that configuration file (and any configuration files it includes). If you then modify the value of any of those build settings in the target or project, the new value is used instead of the value in the configuration file.
Build settings defined at the target level override any values assigned to those build settings at the project level. Therefore, target-level configurations take precedence over any project-level configurations.