I\'m working on an iOS app project, and add the json-framework project to the workspace. The project navigator on the left shows both projects, and the build scheme selector
See the Xcode user guide: Xcode Concepts -> Xcode workspace under 'Projects in a Workspace Share a Build Directory'.
All projects in a single workspace share a build directory. Dependencies are discovered automatically and build if needed:
"Xcode examines the files in the build directory to discover implicit dependencies. For example, if one project included in a workspace builds a library that is linked against by another project in the same workspace, Xcode automatically builds the library before building the other project, even if the build configuration does not make this dependency explicit. You can override such implicit dependencies with explicit build settings if necessary. For explicit dependencies, you must create project references."