Xcodebuild flag reference for CI:
-project OR -workspace
What xcode project/workspace file we're using. If you specify a project on the command-line and that project has an associated workspace, the project is still aware of its existence within the workspace. As an example, worspace level schemes will be available to xcodebuild even if you specify a project on the command line.
Specify the scheme to use for build. Schemes specify multiple build/test targets along with environment args and command line parameters. Schemes must be marked "shared" in the xcode UI in order to be available to xcodebuild. For any particular build/test action there is a default configuration when you use a scheme from the Xcode UI.