Command /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/clang failed with exit code 1

Question

Can't understand how to fix it and why it appears?

    Ld /Users/atencion/Library/Developer/Xcode/DerivedData/Flylista-gcadfttyrgznkmafzaicacwytfey/Build/Products/Debug-iphonesimulator/Flylista.app/Flylista normal i386
    cd "/Users/atencion/Documents/Applications Development/Xcode Projects/Flylista"
    setenv MACOSX_DEPLOYMENT_TARGET 10.6
    setenv PATH "/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin"
    /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/clang -arch i386 -isysroot /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator5.0.sdk -L/Users/atencion/Library/Developer/Xcode/DerivedData/Flylista-gcadfttyrgznkmafzaicacwytfey/Build/Products/Debug-iphonesimulator -F/Users/atencion/Library/Developer/Xcode/DerivedData/Flylista-gcadfttyrgznkmafzaicacwytfey/Build/Products/Debug-iphonesimulator -filelist /Users/atencion/Library/Developer/Xcode/DerivedData/Flylista-gcadfttyrgznkmafzaicacwytfey/Build/Intermediates/Flylista.build/Debug-iphonesimulator/Flylista.build/Objects-normal/i386/Flylista.LinkFileList -mmacosx-version-min=10.6 -Xlinker -objc_abi_version -Xlinker 2 -fobjc-arc -Xlinker -no_implicit_dylibs -D__IPHONE_OS_VERSION_MIN_REQUIRED=50000 -framework QuartzCore -framework UIKit -framework Foundation -framework CoreGraphics -o /Users/atencion/Library/Developer/Xcode/DerivedData/Flylista-gcadfttyrgznkmafzaicacwytfey/Build/Products/Debug-iphonesimulator/Flylista.app/Flylista

ld: duplicate symbol _OBJC_CLASS_$_FlightsViewController in /Users/atencion/Library/Developer/Xcode/DerivedData/Flylista-gcadfttyrgznkmafzaicacwytfey/Build/Intermediates/Flylista.build/Debug-iphonesimulator/Flylista.build/Objects-normal/i386/FlightViewController.o and /Users/atencion/Library/Developer/Xcode/DerivedData/Flylista-gcadfttyrgznkmafzaicacwytfey/Build/Intermediates/Flylista.build/Debug-iphonesimulator/Flylista.build/Objects-normal/i386/FlightsViewController.o for architecture i386
Command /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/clang failed with exit code 1

Answer 1

The actual error is right there in front of you. It appears that your link phase is failing due to a duplicate symbol: FlightsViewController. You've probably defined this twice, or perhaps you've linked it into a library as well as into your main build.