Unfortunately the project consists of more than just the test.xcodeproj file.
What you need to do is go up one level to the folder above and compress the project at that level. in other words if you select that upper level folder you should see two items in that folder. One is a file named Test.xcodeproj and the other is a folder named Test. Like this example:
I was able to add the contents of that zip file you just sent to the other you sent me and assemble the project. It compiles and runs on the simulator just fine so I am puzzled at what is going wrong on your machine.
how strange! I put all the projects in the trash and tried a new one and still same issue.
How can I completely delete the existing projects from XCode? how can I “clean” xcode from all the old stuff so it is completeyl empty? is ist reset, reinstall or re-something? Maybe this is the only way, I get rid of the bug.
It seems like there is something wrong with it so the best thing to do is go to your Applications folder and delete it, then open up the App Store application and re-install it.