I am using ASI (ASIHTTPRequest, ASIDownloadCache, Reachability etc) request. Now in my project, I am using reachability.h and .m file.I have added one third party library and in that library I came to know that they are also using ASI library.
But as per my knowledge they are using ASIReachability class instead of Reachability. So I added that .h file as well.
Still I am getting linker error which says :
duplicate symbol _kInternetConnection in:
/Users/goutham.v/Library/Developer/Xcode/DerivedData/My_TWCable-fyaebjpvvaprmgdgtirhzshodpky/Build/Intermediates/My TWCable.build/Debug-iphonesimulator/My TWCable.build/Objects-normal/i386/Reachability.o
/Users/goutham.v/Desktop/SVN/TWC_BC/12Mar2014_TWCBC/weandsf/iphonesimulator/libWeANDSFLibrary.a(ASIReachability.o)
duplicate symbol _kLocalWiFiConnection in:
/Users/goutham.v/Library/Developer/Xcode/DerivedData/My_TWCable-fyaebjpvvaprmgdgtirhzshodpky/Build/Intermediates/My TWCable.build/Debug-iphonesimulator/My TWCable.build/Objects-normal/i386/Reachability.o
/Users/goutham.v/Desktop/SVN/TWC_BC/12Mar2014_TWCBC/weandsf/iphonesimulator/libWeANDSFLibrary.a(ASIReachability.o)
duplicate symbol _kReachabilityChangedNotification in:
/Users/goutham.v/Library/Developer/Xcode/DerivedData/My_TWCable-fyaebjpvvaprmgdgtirhzshodpky/Build/Intermediates/My TWCable.build/Debug-iphonesimulator/My TWCable.build/Objects-normal/i386/Reachability.o
/Users/goutham.v/Desktop/SVN/TWC_BC/12Mar2014_TWCBC/weandsf/iphonesimulator/libWeANDSFLibrary.a(ASIReachability.o)
duplicate symbol _kConnectionDown in:
/Users/goutham.v/Library/Developer/Xcode/DerivedData/My_TWCable-fyaebjpvvaprmgdgtirhzshodpky/Build/Intermediates/My TWCable.build/Debug-iphonesimulator/My TWCable.build/Objects-normal/i386/Reachability.o
/Users/goutham.v/Desktop/SVN/TWC_BC/12Mar2014_TWCBC/weandsf/iphonesimulator/libWeANDSFLibrary.a(ASIReachability.o)
ld: 4 duplicate symbols for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Please help me. Thanking you.
You've receive duplicate symbol error. So you've to search this string _kConnectionDown, _kReachabilityChangedNotification, _kLocalWiFiConnection, _kInternetConnection, and remove duplication from files. I think, you may import Reachability class twice, one from libWeANDSFLibrary.a and another from ASI. Check this. Hope, help you.
You may be included that files twice in your project so you should remove any one from the project its all because both getting compiled . Choose project--> go to Build Phases--> Type filename which showing it as error and check whether ho many files are there with same name and choose then remove any one from the list
来源：https://stackoverflow.com/questions/22451795/duplicate-symbol-linker-error-due-to-libweandsflibrary-aasireachability-o