iPhone Dev: Base SDK Missing Solved

Someone awesome sent me the code to an iPhone app that he created for RealCajunRecipes.com. I unzipped the file, and opened the project in XCode 4.2. I immediately noticed the upper left hand drop down (what's that called anyway?) said "Base SDK Missing." So I went to all the usual places to change the SDK, I saved it and restarted XCode. Nope, I still encountered the following error when trying to Build my project: error: There is no SDK with the name or path 'iphonesimulator3.1'.

Google searches gave me the same "solution" over and over but none of it worked. Ultimately, I had to go into my projects .xcodeproj directory to edit the file project.pbxproj.

I changed the lines that referenced SDKROOT from SDKROOT = iphonesimulator3.1 to SDKROOT = iphoneos, restarted XCode and successfully built the app.