I ran into an issue with XCode where it wouldn't let me make a clean build. In the build menu, the "Clean" and "Clean All Targets" options were both disabled. I tried changing the build parameters, updating the code, touching the build result, and nothing would work. At the time, I had the "Build Results" window open. Running out of things to do, I closed the "Build Results" window. When I did that, both the "Clean" and "Clean All Targets" options became available. I have no idea why having the "Build Results" window open would affect this. But if your "Clean" and "Clean All Targets" options are disabled in XCode and you want to make a clean build, try closing that window.