title: Linker Command Failed with Exit Code 1 - Duplicate Symbols
body: <p>I am trying to run and test my app in Xcode 8.2.1, but I am getting this error.  I've been searching around, but cannot find an answer that works for my problem.  What could be the culprit here?</p>
  
  <blockquote>
    <p>duplicate symbol _randomPositionY in:
        /Users/tetadickens/Library/Developer/Xcode/DerivedData/Stealth_Crash-gbxbrdfgfsyxnkafhbmltuvxvsvz/Build/Intermediates/Stealth Crash.build/Debug-iphonesimulator/Stealth Crash.build/Objects-normal/x86_64/ViewController.o
        /Users/tetadickens/Library/Developer/Xcode/DerivedData/Stealth_Crash-gbxbrdfgfsyxnkafhbmltuvxvsvz/Build/Intermediates/Stealth Crash.build/Debug-iphonesimulator/Stealth Crash.build/Objects-normal/x86_64/AppDelegate.o
    duplicate symbol _Y in:
        /Users/tetadickens/Library/Developer/Xcode/DerivedData/Stealth_Crash-gbxbrdfgfsyxnkafhbmltuvxvsvz/Build/Intermediates/Stealth Crash.build/Debug-iphonesimulator/Stealth Crash.build/Objects-normal/x86_64/ViewController.o
        /Users/tetadickens/Library/Developer/Xcode/DerivedData/Stealth_Crash-gbxbrdfgfsyxnkafhbmltuvxvsvz/Build/Intermediates/Stealth Crash.build/Debug-iphonesimulator/Stealth Crash.build/Objects-normal/x86_64/AppDelegate.o
    duplicate symbol _randomPositionX in:
        /Users/tetadickens/Library/Developer/Xcode/DerivedData/Stealth_Crash-gbxbrdfgfsyxnkafhbmltuvxvsvz/Build/Intermediates/Stealth Crash.build/Debug-iphonesimulator/Stealth Crash.build/Objects-normal/x86_64/ViewController.o
        /Users/tetadickens/Library/Developer/Xcode/DerivedData/Stealth_Crash-gbxbrdfgfsyxnkafhbmltuvxvsvz/Build/Intermediates/Stealth Crash.build/Debug-iphonesimulator/Stealth Crash.build/Objects-normal/x86_64/AppDelegate.o
    ld: 27 duplicate symbols for architecture x86_64
    clang: error: linker command failed with exit code 1 (use -v to see invocation)</p>
  </blockquote>
  
  <p>EDIT</p>
  
  <p>This issue started after I went to Editor > Validate Settings.</p>