Late 2011 Macbook Pro with 10.9 Mavericks.
I am unable to delete the Working.1 and main.cpp files off of my "Working" project. I had an error at first asking to change the deployment target to 10.8 which I did and that seemed to have removed the error. Yet when I try to drag and copy an exercise file I've referenced to my "Working" project, nothing appears. I had to go into finder and drag it from there, but it still won't show up in Xcode. What am I doing wrong?
Have you tried to restart your mac? It seems like this could just be a small problem with the file system.
If this does not work, reinstalling Xcode may be necessary. I also see that this is the Xcode 4 IDE, Xcode 5 is the newest IDE from Apple to build apps, have you tried to install Xcode 5?