In general, this error is due to the fact that you have updated the version of Xcode, or if you have deleted the previous one and then re-installed the Xcode again, this problem will occur from time to time.
The solution is simple, just go to the directory and delete something. Look at the following actions:
1) Click "Go" in the Finder.
2) I can't see anything, and I want you to hold down the option key in the lower-left position of your keyboard, you will get a resource library.
Because the repository is a system of hidden files, storage of a considerable number of system-related files, in case the small rookie accidentally deleted some files, Apple had to hide it to be foolproof.
The option will only appear if you hold it down, so you can't intercept the picture.
3) go to the library and follow the arrows in the image to find the appropriate folder and delete the contents. (When I was working, I deleted the deriveddata, because I didn't have any important items in there.)
4) Finally, re-run your project again, and that's it. (Remember, after the deletion, immediately exit the "library", and so accidentally damaged the other files, it will have to re-install the system)
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11th Chapter, End!
IOS Programming Xcode Error: Apple LLVM 6.0 Error Resolution