There are several other things you can try:
Check xcodebuild version
Make sure your xcodebuild version xcodebuild also set to 6.4 .

clear all
You probably want to try clean all in the project. Sometimes this is a reset problem.
Clear DerivedData and Xcode Cache Data
Another thing that might cause the problem is that you may need to erase your DerivedData folder along with the Xcode cache.
echo "Removing DerivedData and Xcode Cache" rm -rf ~/Library/Developer/Xcode/DerivedData rm -rf ~/Library/Caches/com.apple.dt.Xcode
Give them a whirlwind and I will update the answer accordingly. Good luck
cnoon
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