Building an application in Xcode takes several steps. We call these steps build phases, and you saw them earlier in this chapter when you added the Core Location framework to the Whereami target (Figure 4.2). Here is what each build phase does:
This build phase contains the source code files that are compiled when this target is built. By default, any time you add a source code file to a project, it is added to this build phase.
After your source code has been compiled, it is linked with the frameworks (libraries). This allows your code to use classes from these frameworks.
After your code is compiled and linked, ...