以下の xcode に次のエラーがあります。これらの原因について何か考えはありますか?
arm-apple-darwin10-llvm-g++-4.2: /Users/<foldername>/Library/Developer/Xcode/DerivedData/Build/Products/Debug-iphoneos/libbtexternal.a: No such file or directory
arm-apple-darwin10-llvm-g++-4.2: /Users/<foldername>/Library/Developer/Xcode/DerivedData/Build/Products/Debug-iphoneos/libbtexternal.a: No such file or directory
lipo: can't figure out the architecture type of: /var/folders/1x/_btz9s41381cdzz41ty0r5fm0000gn/T//cc8KPWhc.out
error: linking step of external dylib build failed, probably due to missing framework or library references - check the contents of the btexternal.ios file
Command /bin/sh emitted errors but did not return a nonzero exit code to indicate failure