Xcode : */swiftc failed with exit code 11, what can I do?

Question

I downloaded Xcode 7 beta 5, and I tried to compile my project with Xcode 7, and it worked. So, after that, I used Xcode 7 to develop my application, but now, I want to back

Answer 1

If cleaning the project & recompiling it doesn't work then

• Quit XCode
• Delete the /Library/Developer/XCode/Derived Data folder
• Start XCode again and compile

Note: this error can happen when using XCode 6.x and XCode 7.x installed (and used) parallel.