This should be a problem with the installation. Reinstall iOSOpenDev and check if there are errors in its installer log. I had the same problem and resolved it using the following two steps.
1) xcode-select must point to the correct xcode location, for example run the following line in Terminal:
$ sudo xcode-select --switch /Applications/Xcode.app/Contents/Developer
2) You must agree xcode license in Terminal
$ sudo xcodebuild -license
$ xcodebuild -license
After that, reinstall the tool and it should work.
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