Xcode Multiple Static Libraries and Duplicate Symbols

question:

I'm developing an iPad application which relies on two static utility libraries (libBFSDK & libBetfair-Platform). Both static libraries include AFNetworking. When I try to include the two static libraries in my iPad application, I get a linking error like:

duplicate symbol _OBJC_METACLASS_$_AFImageCache in:
/Users/osheas/Library/Developer/Xcode/DerivedData/Betfair-gnnjnwtovdmtoxakuxbjyvetciyy/Build/Products/Debug-iphonesimulator/libBFSDK.a(UIImageView+AFNetworking.o)
/Users/osheas/Library/Developer/Xcode/DerivedData/Betfair-gnnjnwtovdmtoxakuxbjyvetciyy/Build/Products/Debug-iphonesimulator/libBetfair-Platform.a(UIImageView+AFNetworking.o)
ld: 86 duplicate symbols for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)

UIImageView+AFNetworking is part of AFNetworking. Both static libraries include AFNetworking. As a result, I get duplicate symbols for UIImageView+AFNetworking.

analyse:

-all_load Loads all members of static archive libraries.

-ObjC Loads all members of static archive libraries that implement an Objective-C class or category.

-force_load (path_to_archive) Loads all members of the specified static archive library. Note: -all_load forces all members of all archives to be loaded. This option allows you to target a specific archive.

solution:

default value of Other Linker Flags  is -All_Load. we can remove -All_load from Other Linker Flags and set -ObjC. question is solved.